Mms

This change adds support for GPRS provisioning via a new plugin "android_provision" which is able to process the AOSP source apns-conf.xml file.

The plugin will create TYPE_INTERNET contexts ( it can create multiple for a single operator ) for those apns that specify the prefix "default" in the "type" attribute of the apn.  It also will create standalone TYPE_MMS contexts if the apn specifies type="mms".

It also adds support for combined Internet/MMS contexts by allowing MessageCenter and MessageProxy properties to be set on TYPE_INTERNET contexts in addition to TYPE_MMS.

In order to test, the ofono upstart override file ( /etc/init/ofono.override ) needs to be manually updated to change "provision" to "android_provision".  Also note that "mbpi" can be removed from the plugin list as well, as it's not actually a plugin.

This has been tested on a mako running image #237.

Note, network-manager will attempt to activate the contexts provisioned in sequence until it finds a context that works.  This may result in the technology indicator flashing on/off until NM finds the valid context.