fixed NPE issue getCollectionItems API
added constants for ScollectionServiceImpl
Merge remote-tracking branch 'gooru/master'
Merge remote-tracking branch 'gooru/master'
Merge remote-tracking branch 'gooru/master'
Merge remote-tracking branch 'goorus/master'
added constants for ConstantProperties
Merge remote-tracking branch 'gooru/master'
Removed skipPagination and added relevant changes with few exceptions.
Merge branch 'master' of https://github.com/cyrilraja/Gooru-Core-API

Conflicts:
	gooru-
core/src/main/java/org/ednovo/gooru/core/constant/ConstantProperties.java
Removed unused codes and added code improvements
Merge remote-tracking branch 'goorus/master'
added constants for FeedbackServiceImpl

Conflicts:
	api/src/main/java/org/ednovo/gooru/domain/service/FeedbackServiceImpl.java
added constants for ResourceServiceImpl
added constants for SessionServiceImpl
added constants for TagServiceImpl

Conflicts:
	api/src/main/java/org/ednovo/gooru/domain/service/tag/TagServiceImpl.java
added constants for FeedbackRestV2Controller
Merge remote-tracking branch 'gooru/master'
added constants for LibraryRestV2Controller
added constants for ResourceRestV2Controller