standardize plugins, update metadata

add about-plugin metadata
chmod -x plugins
cleanup filenames to standardize on x.plugin.bash format
only plugin files intended to be executable from the command line should
contain a shebang line, and should be a+x.

plugins/available/virtualenv.plugin.bash

@@ -1,19 +1,30 @@
-#!/usr/bin/env bash
-
 # make sure virtualenvwrapper is enabled if available
+
+cite about-plugin
+about-plugin 'virtualenvwrapper helper functions'
+
 [[ `which virtualenvwrapper.sh` ]] && . virtualenvwrapper.sh
 
-# create a new virtualenv for this directory
+
 function mkvenv {
+  about 'create a new virtualenv for this directory'
+  group virtualenv
+
   cwd=`basename \`pwd\``
   mkvirtualenv --no-site-packages --distribute $cwd
 }
 
-# create a new virtualenv for the branch you're currently in
+
 function mkvbranch {
+  about 'create a new virtualenv for the current branch'
+  group virtualenv
+
   mkvirtualenv --no-site-packages --distribute "$(basename `pwd`)@$(git_prompt_info)"
 }
 
 function wovbranch {
+  about 'sets workon branch'
+  group virtualenv
+
   workon "$(basename `pwd`)@$(git_prompt_info)"
 }