(This is a merge of http://go/wvgerrit/11613 from the Widevine CDM repo.) Adds a property for the OS version, implements it on Android, and adds it to the license request property bag so that Netflix may use it to discern the supported capabilities of the CDM. Bug: 18230738 Change-Id: If5174a108093855314f3e0102b83691e20bb247b