Closes #374: Truncating x-axis should be done to ticktext not x values.

[emtwo]

For some context/background:

1. This commit originally did x-axis truncation but only for pie charts: 3087822
2. A similar method of truncation was used in this commit to also be applied to other charts: eb1b3cb
3. Issue Redash visualizations not rendering for some number types #374 came up because when x-axis values were numeric, the attempt to truncate them failed. This turned out to be the case for pie charts too but I suppose they aren't used as often so the issue was not filed sooner.
4. This PR keeps tickvals as the original numeric values but adds an additional array of truncated text, ticktext. The truncation issue should still be resolved as well as the ability to have numeric x-axis values.

Here are a couple of queries to test with:

For numeric x-axis:

WITH sample AS
    (select 26191 as a, 121370 as b, 21.58 as c union
     select 26591 as a, 121170 as b, 11.53 as c union
     select 26598 as a, 121170 as b, 22.58 as c union
     select 26594 as a, 121170 as b, 41.58 as c union
     select 26592 as a, 121170 as b, 51.58 as c union
     select 16596 as a, 121170 as b, 11.58 as c union
     select 26593 as a, 121170 as b, 31.58 as c union
     select 26597 as a, 121170 as b, 81.58 as c union
     select 56599 as a, 121170 as b, 21.58 as c)
select a, b, c from sample

For correctly truncated x-axis:

WITH sample as (
    select '2017-12-10 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-11 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-12 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-13 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-14 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-15 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-16 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-17 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-18 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-19 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-20 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-21 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-22 00:00' as x, 'US' as type, 8215767 as foo union
    select '2017-12-23 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-24 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-25 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-26 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-27 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-28 00:00' as x, 'US' as type, 8215767 as foo union
    select '2017-12-29 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-30 00:00' as x, 'US' as type, 8215767 as foo union
    select '2017-12-31 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-32 00:00' as x, 'US' as type, 8215767 as foo union
    select '2017-12-33 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-34 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-35 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-36 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-37 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-38 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-39 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-40 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-41 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-42 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-43 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-44 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-45 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-46 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-47 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-48 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-49 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-50 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-51 00:00' as x, 'US' as type, 574047 as foo union
    select '2017-12-52 00:00' as x, 'ROW' as type, 8215767 as foo)
select * from sample

[jezdez]

rwc+

[jezdez]

Looks good to me, I didn't know about ticktext, looking at https://plot.ly/javascript/axes/#enumerated-ticks-with-tickvals-and-ticktext made it more clear what it looks like. Maybe add a comment on where that comes from?