Added last_update datetime column to db.
Updated test data and csv->db mappings.
Updated Item Model to use new last_update column.
Merge branch 'master' into CCH-1110
Merge branch 'master' into CCH-1110
Adding HEAD request to the Item REST API.
Merge pull request #784 from isuftin/master

Legend fixes/refactoring
Refactored Legend.js a bit to push down ajax calls outside of init
Further refactoered legend to give more control for how each type of item is processed
Refactored legend creation to give more control to the table-type discovery functions
Merge pull request #785 from isuftin/master

back of card buttons grouped together
Merge branch 'master' of https://github.com/USGS-CIDA/coastal-hazards into legend-update
renaming column
CCH-1090 - First pass at printing
Merge pull request #787 from isuftin/legend-update

Accidentally added checkins to this feature branch for CSS Print functionality
Updated for ribboned layers to group legends properly
Merge pull request #788 from isuftin/legend-update

Updated for ribboned layers to group legends properly
Merge pull request #786 from cschroed-usgs/CCH-1110

Cch 1110