Ruby Switching Helpers

Add helper functions to switch gemsets on ruby-1.8.7-p334 and ruby-1.9.2-p180.
Add completion definitions for helper functions.

plugins/rvm/rvm.plugin.zsh

 fpath=($ZSH/plugins/rvm $fpath)
 autoload -U compinit
 compinit -i
+
+local ruby18='ruby-1.8.7-p334'
+local ruby19='ruby-1.9.2-p180'
+
+function rb18 {
+	if [ -z "$1" ]; then
+		rvm use "$ruby18"
+	else
+		rvm use "$ruby18@$1"
+	fi
+}
+
+_rb18() {compadd `ls -1 $rvm_path/gems | grep "^$ruby18@" | sed -e "s/^$ruby18@//" | awk '{print $1}'`}
+compdef _rb18 rb18
+
+function rb19 {
+	if [ -z "$1" ]; then
+		rvm use "$ruby19"
+	else
+		rvm use "$ruby19@$1"
+	fi
+}
+
+_rb19() {compadd `ls -1 $rvm_path/gems | grep "^$ruby19@" | sed -e "s/^$ruby19@//" | awk '{print $1}'`}
+compdef _rb19 rb19