FLOE-195: Implement the mismatch details dialog

The related JIRA: http://issues.fluidproject.org/browse/FLOE-195

The feedback tool test plan has been updated with how to test the mismatch details dialog: http://wiki.fluidproject.org/display/fluid/Metadata+Feedback+Tool+QA+Test+Plan

One issue with the implementation in this pull request is, there are situations that two tooltips, or one dialog and one tooltip, are showing at the same time. This issue will be address in http://issues.fluidproject.org/browse/FLOE-226
We should give this a more meaningful name reflecting its purpose. The _ invites the reader to imagine that this is somehow related to a CouchDB document field, for example.