Add TinyMCE to Contribution textarea

[zerocrates]

Imported from Trac ticket #154 reported by jboggs on 2011-02-11:

Add the TinyMCE editor to the textarea of the public contribution form, with a limited set of allowed tags and attributes. Could also be optionally turned on/off from the plugin's configuration panel.

[zerocrates]

Comment by jflatnes on 2011-02-11:

This touches a more general problem: our general TinyMCE code and other Omeka JS globals are all in the admin-side globals.php.

We should probably segregate some subset of those that are truly global into an application/views/scripts/javascripts/globals.js, and move the admin-side-specific stuff elsewhere.