Added initial zsh completion support to git_index

zsh now completes all arguments and all directories inside $GIT_REPO_DIR. This is till buggy because not all directories in $GIT_REPO_DIR are actual git projects. Next update will include completing the list in the .git_index file.
Eliminated zsh references in completion

Since there is another, totally different completion function, this patch eliminates
all references to zsh in _git_index_tab_completion.
Merge branch 'master' of git://github.com/ndbroadbent/scm_breeze
Conditional git branch aliases definition
Merge pull request #83 from grota/master

Conditional git branch aliases
Set up demo git user for tests
Updated demo user setup
Updated readme [ci skip]
Update README [ci skip]
Merge branch 'master' of git://github.com/ndbroadbent/scm_breeze
Make bash completions work with Ubuntu 13.04
Merge pull request #86 from mbachry/master

Make bash completions work with Ubuntu 13.04
Fix gb -D expansion
Adds git stash aliases
Merge pull request #94 from abhshkdz/master

Git stash aliases
Merge pull request #89 from siasia/master

Fix gb -D expansion
Add git difftool (default alias "gdt")
Added 'git_reset_last_commit' (grsl) alias, useful for undoing a temporary commit
repo_index should be case insensitive
Fixed case-insensitive matching... my last commit was pretty dumb