Support nested pseudo-classes and parent reference (LESS)

[nponiros]

JavaScript:
css beautifier checks if the colon it encounters
is part of a property: value or part of a nested pseudo-class/
parent reference. In case of nested pseudo-class or parent reference (LESS)
it does not output a space after the colon.

Added general test for parent reference, nested pseudo-class and
SASS import statement. Added special test for issues #410 and #414.

Python:
Best effort to support parent reference and nested pseudo-class.
When it encounters a colon it checks if the colon is part
of a property: value or part of parent reference/nested pseudo-class.
In case of parent reference/nested pseudo-class it does not output
a space after the colon.

Added tests for reference/nested pseudo-class. Add tests for
issues #410, #414

Fixes issues #410 and #414
Related to issue #356

[nponiros]

I saw that some people already have opened similar pull requests but I needed that for my projects so I wrote it and figured opening a pull request doesn't cost :)

Unfortunatelly I am not much of a python developer so the python changes might not really be good..

Regards
Nikolas

[noducks]

Awesome. Great to see a fix for this.

[nightspirit]

Try this code with brackets-beautify https://github.com/drewhjava/brackets-beautify

It's not even beautify less file at all. Have no idea what's going on.

[bitwiseman]

I believe the issues addressed here are now fixed. But I have not integrated all the tests from this PR into master.

[bitwiseman]

Thanks for this work. I think I got the key points, so we don't kill these anymore, but I'm sure I left a few more issues that need addressing. Any additional help you want to provide would be much appreciated.