Allow custom tags

[JeremiePat]

It would be nice to allow users to add custom tags of their own. For examples: technologies, company names, etc. This would provide a nice way to filter and group resources.

[toolness]

So while I haven't yet added this, I did just add full-text search in 64ff576, which will hopefully help with the filtering/grouping issue. For instance, here are all the resources with "scratch" in their name or description:

http://weblitmapper.webmakerprototypes.org/?filter=scratch