Change license from CC BY-SA to the MIT license

Refs #299.
Fix issues in Arch Linux PKGBUILDS

Closes #291.
Fix minor typo in powerline.vim
Add Travis build status to README
Output in either otf or ttf (so we don't loose hinting/whatever)
Preserve style suffixes by inserting ForPowerline before any '-'s
Add bzr support
Cleanup .gitignore file
Fix set statusline location, readd fix from #243

Ref #303
Move argparser to powerline.shell so it can be re-used
Add vim modelines to all Python files

Added with `sed -i '2i# vim:fenc=utf-8:noet' `find -name '*.py'`` and
fixed in a couple of files without the UTF-8 encoding on top.

Ref #314
Merge remote-tracking branch 'pdf/ttf_output' into develop
Add XDG_CONFIG_DIRS to config_paths for system-wide install

Commonly this will be `/etc/xdg/powerline`
Combine vim modelines and Python encoding declarations

Ref #314