Treat GDB communication as raw data (Closes: #634834)

	* src/dbgengine/nmv-gdb-engine.cc
	(GDBEngine::Priv::set_communication_charset): Support treating
	communication data as binary.
	(GDBEngine::Priv::launch_gdb_real): Treat our communication with
	GDB as binary communication.
	(GDBEngine::on_gdb_stdout_has_data_signal): Use std::string
	instead of UString to handle data we get from GDB.
	* src/dbgengine/nmv-gdbmi-parser.cc
	(GDBMIParser::parse_octal_escape_sequence): Treat octal escape
	sequence as representing file paths for now.