Fix branch name colors (bash)

Thanks @jagipson :)

Update zsh installation instructions.

 * Add support for fish.

 * Update zsh completions and descriptions.

Sort branch lists so comm does not complain.

(thanks matzko!)

Fix incorrect labels for 'feature' in zsh.

Fix copypasta and whitespace for zsh.

* Better autocompletion for `feature track` and `release track` ... O…

…nly suggest branches which are not already tracked.

* Don't suggest 'track' or 'publish' for hotfixes.

Add support for git-flow 0.4 (bash only).

* Fix a bug with remote feature autocompletion

* Speed up listing feature and release branches 25x

Revert __git_find_on_cmdline / __git_find_subcommand swap.

Better autocomplete results for 'git flow feature track'.