bin/ide: allow many possibilities for projects directory
.zsh/aliases.zsh: alias chown and chmod commands to their gnu equivalent on MacOSX (otherwise they don't support suffixing options)
.zsh: alias df to gdf on MacOSX
.zsh: improve rvm path loading (support for user-based installations)
.zsh: remove screen-specific hack now that I use tmux exclusively
bin/ide: remove screen-related things
bin/ide: don't launch a server if the app can be automatically launched by Pow
bin/ide: don't launch tests automatically on redmine instances