Porting advanced embargo function to JSPUI

Fixed some codes as the code reviews by helix84

reverted the api of BrowseItem to its original

revert build.properties

Porting advanced embargo function to JSPUI, revised version
correct some strings and comments
Merge remote-tracking branch 'helix84/zuki-embargo3-rebased' into DS-1360

Conflicts:
	dspace-api/src/main/resources/Messages.properties
	dspace-jspui/src/main/webapp/styles.css
Renamed xmlui.submission.restrictstep.* configuration parameters to webui.submission.restrictstep.*
Renamed xmlui.submission.restrictstep.* configuration parameters to webui.submission.restrictstep.*
Organize import, wrong header for end date column
Avoid advanced form to repropose the first embargo policy after any confirm & add
added a license header
Merge pull request #298 from abollini/DS-1360

DS-1360 Porting advanced embargo function to JSPUI