Update rvm.plugin.zsh to the latest ruby versions

Ruby version numbers update:
1.8.7-p371
1.9.3-p392
2.0.0-p0

plugins/rvm/rvm.plugin.zsh

@@ -3,9 +3,9 @@ fpath=($rvm_path/scripts/zsh/Completion $fpath)
 alias rubies='rvm list rubies'
 alias gemsets='rvm gemset list'
 
-local ruby18='ruby-1.8.7-p334'
-local ruby19='ruby-1.9.3-p385'
-local ruby20='ruby-2.0.0-rc2'
+local ruby18='ruby-1.8.7-p371'
+local ruby19='ruby-1.9.3-p392'
+local ruby20='ruby-2.0.0-p0'
 
 function rb18 {
 	if [ -z "$1" ]; then