Reenable the note search API

Add a postgress freetext index on the note comments, and enable
note searching using freetext matching.
Change attribute names for diary/message titles to match UI labels
Highlight erroneous fields by adding a class to them

The default rails scheme for highlighting errors is to wrap the
field in a div, but that changes the structure of the page and can
change the meaning of CSS rules applied to the fields.

As an alternative we now apply a class to the fields, and use that
in the CSS to apply a highlight.