Make vcs segments *much* faster

Do not call vcs status unless the relevant files have changed.
Uses inotify, if available, otherwise falls back to stat() based
monitoring. Fixes #396
Move --config and --theme_option processing to finish_args
Use deepcopy in powerline.lib.config
Fix tmux cwd segment

Fixes #467

Still needs colors for cwd:current_folder, cwd and cwd:divider
Fix tmux tests
Also fix bash tests
Remove debugging lines
Segment to Print Environment Variables

 - Added segment function to powerline.segments.common.
 - Added test to check return values.
 - Added default colorschemes for everything but iPython.

Ref #477
Fix tests failing if inotify not available
Forgot to move the import to module level
Turn off status colors by default in vim as well
Add a debug() function to allow command line debugging of the vcs code
Merge remote-tracking branch 'kovidgoyal/vcs' into develop
Merge remote-tracking branch 'zyx-i/powerline-daemon' into develop
Reset emulate call:

- only emulate -L causes options to be restore after function call
- using setopt outside of functions does not reintroduce #342
Add __contains__ method

Fixes #471
decode takes no keyword arguments in python-2.6
Always return true in install.sh
Fix typo in scripts/powerline
Merge remote-tracking branch 'zyx-i/zsh-emulate' into develop