GitLab

I've changed it to use `view` instead of `vim -R` to make it hopefully
more editor-agnostic.

In detail:
gup - now completes with remotes like git fetch would
gdv - got git diff completions
gc/gca - now zsh will suggest files in staging area
gba - suggestions as for git branch

fixed typo in rails3 plugin and added one alias for migrating and redoing migration if it was successful

If the svn plugin is used, svn info (repo name and wether the repo is dirty) is displayed in the prompt like with git. Just lke with git, the colors can be manipulated with variables (see awesomepanda theme for example).

Reorganizing plugins so that each plugin has it's own directory now so that any plugin-specific functions can be bundled within there.