Updating SDK version to 2.1.3
Merge pull request #539 from khawkins/master

Updating SDK version to 2.1.3
Merge remote-tracking branch 'origin/master' into unstable

Conflicts:
	shared/SalesforceSDKCore/SalesforceSDKCore/Classes/Common/SalesforceSDKConstants.h
Merge pull request #540 from khawkins/unstable

Mobile SDK: Merging master into unstable