Fix issue #197: quote OMF_PATH

Support omf- prefix for packages

bugfix: add missing $s in variable tests in git_ahead.fish

Run tests on osx

Unfortunately we can't use docker anymore in order to support automatic
build on OSX.

Better test output

OSX `date` does not support milliseconds output, so @derekstavis created
this `C` code to generate the time with milliseconds.

Show name of the test that failed with the failure message.

Better organized 'omf theme' output

Headings are underlined.
Current theme is highlighted in the Installed category.

Test suite

registry: add oh-my-fish/plugin-balias

add powerline

rename plugin

registry: Add iex&mix plugins

Until omf support omf- prefix.

Faster CI builds

Tell Travis this is not Ruby codebase.

Add homebrew command not found plugin

omf/templates: Align README headers based on omf's

Revamp current logo, use SVG version on README

Use rawgit to serve assets with correct Content-Type.

- Complete redraw with pixel alignment by design
- Use a image size of 1024 x 1024px
- Base logo alignments on iOS 7 icon grid
- Use background corner rounding of 48px
- Optimize SVG file with svgo tool (minification)

registry: Add shark plugin

readme: Fix wrong link to FAQ

* The English README.md had a link to FAQ that does not work anymore
  given that it has been localized to `zh-CN` too. This commit makes
  sure that the link to FAQ in the English article points to the correct
  part of the correct file.