Bump GWT to 2.7.0
Bump GWT to 2.7.0

Change-Id: Ibbebf86b42992ca300524f2c1f08db10028f63c3

GerritCodeReview/plugins_serviceuser,GerritCodeReview/plugins_serviceuser,GerritCodeReview/plugins_serviceuser,GerritCodeReview/plugins_serviceuser,GerritCodeReview/plugins_serviceuser