Add powerline documentation.
Update powerline hash and add Powerline_symbols variable.
Changes in vimrc:
* Remove commented out lines.
* Change TagbarOpen to TagbarToggle when opening a python file.
* Add note for Spacebar mapping
* Remove vim-coffee-plugin stuff, I don't use it.
* Add DEFAULT values of python-mode plugins settings.
* Comment out Tlist specific changes, we already have Tagbar.
Remove vim-taglist, we already have tagbar.
Update vim-python-mode to 0.6.18
Further explanation in modules documentation.