fix #1645 at OpenNTF/SocialSDK: BaseEntity.exist
fix #1621 at OpenNTF/SocialSDK: CommunityUrls.SUBCOMMUNITIES
fix #1642 at OpenNTF/SocialSDK: Handle tags well
fix #1641 at OpenNTF/SocialSDK: Store community tags also.
Merge branch 'master' into sbtsdk-1.1.1-inovex.ext
Merge branch 'master' into sbtsdk-1.1.1-inovex.ext

Conflicts:
	sdk/com.ibm.sbt.core/src/main/java/com/ibm/sbt/services/client/connections/communities/CommunityUrls.java
Merge pull request #1646 from inovex/sbtsdk-1.1.1-inovex.ext

Fix several issues in com.ibm.sbt.core code.