Added basic PEP 8 to .travis.yml and fixed currently reported issues. Fixes #147.

[mertemba]

Python and Javascript code is checked for trailing whitespaces and blank lines, unused imports and tab indentation.

Fixes #147

Checklist

• There are no merge conflicts.
• If there is a related issue, a reference to that issue is in the
  commit message.
• The PR passes tests both locally (run nosetests) and on Travis CI.
• The code follows PEP8 guidelines. (use a linter, e.g.
  pylint, to check your code)
• The new feature is documented in the Release
  Notes.
• The code is backwards compatible. (All public methods/classes must
  follow deprecation cycles.)
• All reviewer comments have been addressed.

[moorepants]

This is probably incorrectly removed.

[moorepants]

These are the only JS files that we wrote: https://github.com/pydy/pydy/tree/master/pydy/viz/static/js/dyviz

The ones in external for example of just libraries that we download and we should lint or modify them.

[moorepants]

Likely incorrect.

[moorepants]

@jellysheep I've add a checklist to the top. Please review those items. Some may not be relevant to this PR because you aren't adding code. But once you complete those items, the reviewers will check them off.

[mertemba]

@moorepants Thanks.
However I am sorry, I do not have the time to finish this fix/pull request before the deadline tomorrow, as I am leaving in two hours and will be without access to my computer for two weeks (in spite of the fact that this is easily doable for me with a bit more time, but regarding the original issue title I did not assume that fixing syntax in the whole code was required).

[moorepants]

@jellysheep Ok, do the best you can on your application and do as much work as you can here before you leave. Good luck!

[mertemba]

@moorepants Sorry for the delay, I returned on sunday but was struck down with a cold for a few days.

The removed (and the now checked) whitespaces and imports should be fine now, just leave a comment if something is missing.

I watched the SymPy discussion about formatting PRs, but I think the above comments are ok as they are about PEP8 compliance of the whole codebase, not just minor cosmetic fixes.
If the basic content of this pull request is needed for SymPy as well, I could imagine to integrate this kind of linting there, too.

[moorepants]

Looks good. Thanks for the contribution.