CB-6511 Fixes build for android when app name contains unicode characters

Fix for issue: https://issues.apache.org/jira/browse/CB-6511
Use hardcoded Activity/class name to avoid problems with unicode names. Future improvement - use additional option for cli to specify custom activity/class name (https://issues.apache.org/jira/browse/CB-7231)

More info in threads: http://callback.markmail.org/thread/o7w52dbpiikcivwp and http://callback.markmail.org/thread/2iaojpftpggrmcj6