[dbus] Allow user processes to call reset_config method. Fixes MER#1406

User processes are explicitly allowed to change mce runtime settings,
but resetting the settings back to installationd defaults requires root
privileges.

Add configuration entry to allowing user processes to call also the
reset_config method.

mce.conf

@@ -61,6 +61,9 @@
 		<allow send_destination="com.nokia.mce"
 		       send_interface="com.nokia.mce.request"
 		       send_member="set_config"/>
+		<allow send_destination="com.nokia.mce"
+		       send_interface="com.nokia.mce.request"
+		       send_member="reset_config"/>
 
 		<allow send_destination="com.nokia.mce"
 		       send_interface="com.nokia.mce.request"