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
Fix tests failing if inotify not available
Forgot to move the import to module level
Add ruby_version highlighting group
Add RVM segment
Add RbEnv segment
Added Syntastic Flag Segment
Added Syntastic Segment.

Add a new segment to theme with name 'syntastic_segment' and it will
display the SyntasticStatuslineFlag from syntastic.

Refactored Syntastic Segment

Checking if function SyntasticStatuslineFlag exists in vim first before
getting it's value.

Refactored further
Add unite.vim matcher and theme
[update] add unite and tagbar theme config
Add tagbar matcher
[fix] duplicated unite_segment key in solarized theme
Turn off status colors by default in vim as well
Add a debug() function to allow command line debugging of the vcs code