Handle concurrency issues saving.
#MBL-10432
LESS compile
Added unit tests for diff'ing function in _EditBase.
#MBL-10432
Merge branch 'develop' into topic-concurrency

Conflicts:
	content/css/themes/swiftpage/theme.less
	min/css/themes/swiftpage/sdk.min.swiftpage.css
	min/css/themes/swiftpage/sdk.min.swiftpage.debug.css
	src/_EditBase.js
Use the validation summary to display the concurrency errors. Automatically re-save when no diffs found.
#MBL-10432
Merge pull request #68 from Saleslogix/topic-concurrency

Topic concurrency