Search across all tag sets

basic idea is that we add a new text field to advanced search that allows:

partial tag value searching
e.g. searching "budget" would retrieve contacts tagged with any tags that contain that value (implicit wildcards, both sides)
search across all tags
in the example above, we return contacts in any tags – across both the hierarchy and any tagsets

http://senatedev.senate.state.ny.us/issues/show/4279