#318: replaced jquery.placeholder.js with https://github.com/mathiasbynens/jquery-placeholder
#318: replaced jquery.snippet.js with codemirror
#328: added show and hide buttons to the ShowSource component;
#318: removed unused files
Merge branch 'master' of git://github.com/got5/tapestry5-jquery
Merge pull request #330 from criedel/master

Fix for #318