Allow user processes to make get_config and set_config method calls to mce

At least the settings application needs to use these method calls.
Allow user processes to make get_color_profile method calls

Allows "mcetool --status" to work for non-root users too.
Merge pull request #32 from spiiroin/config_dbus_method_calls

Allow user processes to make get_config and set_config method calls