Add variable for focused input background

[aronstrandberg]

Add a variable to make it possible to configure the input's background color when focused.

I was trying to theme the focused state in a project, but found it bit cumbersome, hence the desire for these changes. I'd be happy to make any requested changes from your side.

[coveralls]

Coverage remained the same at 91.994% when pulling a218808 on aronstrandberg:input-focus-bg into 1c2f096 on JedWatson:master.

[JedWatson]

Thanks @aronstrandberg, happy to accept this addition.

Would you please add it to the scss files as well though? we need to keep them in sync with the less, unfortunately this is a manual process.

[JedWatson]

Please fix this up and add the .scss files as well, as we can merge this 👍

[JedWatson]

Please make this default to @select-input-bg in case that has been customised, otherwise this would be a breaking change.

[coveralls]

Coverage remained the same at 91.994% when pulling ffe5b12 on aronstrandberg:input-focus-bg into 1c2f096 on JedWatson:master.

[aronstrandberg]

@JedWatson Pushed some commits to adress these things. I couldn't find the equivalent of .Select-focus-state in the scss files, so I'm not 100%, but I think they should be similar now – is there a way to test the examples with the scss files to make sure?

[coveralls]

Coverage remained the same at 91.994% when pulling 2fdedda on aronstrandberg:input-focus-bg into 1c2f096 on JedWatson:master.

[coveralls]

Coverage remained the same at 91.994% when pulling 2fdedda on aronstrandberg:input-focus-bg into 1c2f096 on JedWatson:master.

[aronstrandberg]

@JedWatson I just rebased this on master to adjust for upstream changes. Do you think this is ready to merge?

[coveralls]

Coverage remained the same at 92.344% when pulling 535bc23 on aronstrandberg:input-focus-bg into 7523c20 on JedWatson:master.

[aronstrandberg]

@JedWatson?

[JedWatson]

Looks great @aronstrandberg, thanks!

[abdennour]

Do not release feature with big bug :

Failed to compile.

Module build failed: 
		background: $select-input-bg-focus;
             ^
      Undefined variable: "$select-input-bg-focus".
      in /Users/abdennour/workspace/idax/node_modules/react-select/scss/control.scss (line 70, column 15)