SMS 8-bit GSM characters decoding support

Support decoding the user data payload as pack GSM 8-bit (a GSM alphabet
string that's stored in 8-bit unpacked format) characters.

Change-Id: I790dd448a8aaed952d5e24961d9fc509112f7486

Conflicts:
	core/res/res/values/config.xml
	core/res/res/values/symbols.xml