[TreeProjectWidget] Add Compress feature

- Add Compress feature to Project Explorer context menu.
- Using Builtin Std Lib only.
- Add new method _compress_path()
- PEP8 / Lint compliant.
- Update translations.
- Add missing DocStrings.
- This feature can be extended on future.


![temp](https://cloud.githubusercontent.com/assets/1189414/2546202/655bcafa-b62e-11e3-9a5f-f0aa8ca0d206.jpg)


For more info please refeer to: 
- http://docs.python.org/2/library/shutil.html#shutil.make_archive
- http://docs.python.org/3/library/shutil.html#shutil.make_archive

Brancho: feature/compress  :large_blue_circle: