add thumbnail table, store base64 image as "text"
Thumbnail services set up

* we may want the services to do more of the work (calling n52, but for now it just takes a base64 thumbnail)
* added a convenience method to PublishResource for checking whether session is valid for publishing
* GET and PUT are implemented on thumbnail
Merge pull request #610 from jiwalker-usgs/thumbnails

Thumbnails
Merge pull request #611 from isuftin/master

UI updates/bug fixes
Merge conflict resolution
Merge branch 'master' of https://github.com/USGS-CIDA/coastal-hazards

Conflicts:
	coastal-hazards-portal/src/main/java/gov/usgs/cida/coastalhazards/rest/data/ItemResource.java