Copying code from the website also copies the prompts

[nswamy]

Description

When copying code using the Copy from Clipboard javascript on the website, it also is copying the prompt
Go to 1) http://mxnet.incubator.apache.org/install/index.htmlplatform=Linux&language=Python&processor=GPU
2) use the copy to Clipboard option to copy text it has copied,
$ pip install mxnet-cu92 earlier the shell prompt was not copied to clipboard

Environment info (Required):

Mac OS/Google Chrome Version 69.0.3497.100 (Official Build) (64-bit)

@aaronmarkham could you please take a look

[LuckyPigeon]

@nswamy May I do this issue?

[nswamy]

👍 @LuckyPigeon
Yes, your very welcome to submit a PR. If you are interested in contributing to the website, I think @aaronmarkham can help you with some starter tasks.

[aaronmarkham]

Hi @LuckyPigeon - take a look at these website build instructions, so you can test your changes: https://cwiki.apache.org/confluence/display/MXNET/How+to+Build+the+Website
Please let me know if you need any help.

[ys2843]

Current copycode.js has several problems

1. mistakenly creates global variables
2. missing prompt mapping
3. the use of jquery tooltip does not work, because we do not load jquery ui any more

I will rewrite this file and fix this prompt issue.