Install distribute by default
Now lsvirtualenv deploys inve to already existing virtualenvs

this way, the transition from virtualenvwrapper to invewrapper should be eased
Included virtualenvwrapper's test suite
Adapted relevant virtualenvwrapper tests to work with invewrapper
Added sitepackages_dir command, and refactored common code

Changed some print to stderr to be sys.exit, when appropriate
Added add2virtualenv command
Implemented toggleglobalsitepackages, cpvirtualenv, setvirtualenvproject, mkproject, mktmpenv, wipeenv and allvirtualenv

Refactored the code, and added virtualenv-clone as a dependency (for cpvirtualenv)
Added a simple way to define project templates (included template_django as an example)
Adapted all remaining tests and fixed 2 small issues in invewrapper that I discovered with it

Removed useless tests, change the template package to the template file, specified bash as the SHELL for running the tests (otherwise, with fish I wouldn't be able to run some checks)
Added some docstrings for the commands (mostly by copying the virtualenvwrapper's comments)