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 tagbar matcher

Merge branch 'develop' of git://github.com/dhruvasagar/powerline into develop

Conflicts:
	powerline/config_files/colorschemes/vim/default.json
	powerline/config_files/colorschemes/vim/solarized.json
	powerline/segments/vim.py
Add unite.vim matcher and theme
Merge branch 'feature/unite.vim' into develop

Conflicts:
	powerline/config_files/colorschemes/vim/default.json
	powerline/config_files/colorschemes/vim/solarized.json
	powerline/config_files/config.json
Fix typo in json config files