Fix /bin/sh compatibility issue in install.sh
gitfast: update to upstream v1.8.4

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
don't clobber existing RBENV_ROOT & follow Homebrew's default behavior
Added/modified some useful aliases.
catimg plugin
allow to print an image to the stdout using convert
Fix for virtualenv support - fixes #2328, fixes #2297, resolves #2319
Fixed a dirs bug for catimg
catimg: fix exit without using source
supresses errors from convert whilen converting, as they
are usually just warnings
typo fix
Add rdmtc alias for rails plugin.
Prevents oh-my-zsh loading the .zshenv twice
Add support to command "show"
fix name schema for sudo plugin

Plugin won't load automatically if added to variable $plugins, if name schema different than $name/$name.plugin.zsh is used (see is_plugin() in oh-my-zsh.sh).
Fixes rvm_prompt_info() in lib/rvm.zsh
Returns false when rvm is not found.
Returns false when rbenv is not found.
Adds chruby_prompt_info dummy function.
Joins ruby prompt files and adds ruby_prompt_info.
Refactors ruby_prompts.zsh
Fix bad right prompt placing.