COOPR-653: add partial templates REST API endpoints
COOPR-653: improve error message
Merge remote-tracking branch 'upstream/develop' into feature/coopr-653

Conflicts:
	coopr-server/src/main/java/co/cask/coopr/http/handler/AdminHandler.java
Merge remote-tracking branch 'upstream/develop' into feature/coopr-653
Addressed PR comments
Merge remote-tracking branch 'origin/feature/coopr-653' into feature/coopr-617

Conflicts:
	coopr-server/src/main/java/co/cask/coopr/http/handler/AdminHandler.java
	coopr-server/src/test/java/co/cask/coopr/http/AdminHandlerTest.java
COOPR-617: add version to primary key