Initial commit for etl redesign
Filtering via PSM, with visual indicator
Fixed bug in mapping of standard variable
Major Layout changes (fluid containers) and UI updates to header mapping section
UI updates
Cosmetic updates
Proper resolution to make sure None placeholder is not dragged and dropped

Fixed bug where results in combo box had duplicates
Added logic to clear variable data if target object has been moved from one phenotypic group to another
Restored additional details to standard variable data transfer object
UI updates to modal dialog, mapping info
added css class conditional for validations
Added support for Message items whose key is not in Message.properties
Sample implem for error messaging
Merge branch 'etl_v2' of https://github.com/digitalabs/ETLSample into etl_v2

Conflicts:
	src/main/webapp/WEB-INF/pages/angular/angularMapHeaders.html
Included disabling of buttons in 'preview mode'
sample implem server side
GCP-7647 and GCP-7645
Updated ng:class expressions
Updates to preview mode
disable drag+drop on preview mode
bug fixes