Merge pull request #276 from CruGlobal/MH-871

Add encoding headers to avoid invalid byte sequence error in imports
TT - Add Labels to dropdowns
TT year ago date fixes plus labels
Trend Tracker tweaks on labels and options
TT - Change blank to "(none)"; Fix issue when all fields are "(none)"
Merge branch 'MH-637-cl' into dev

Conflicts:
	app/controllers/charts_controller.rb
	app/views/charts/_trend_fields.html.erb