Draft Revision on GSettings for Blueman

Config API Modified to allow schema changes on load
Force python2 Detection on Systems
with python2.x and python3.x installed
Migrate GSettings Schema from apps.blueman to org.blueman
Rename schema files to .schema.xml standard
Rework GSettings.py to use Gio.Settings.new for settings with no
specified path

TODO:

* Testing
* setup auto install for xml files
* remove old File and GConf Support
gsettings: Move schemas to data directory and add autotools bits
gsettings: Remove duplicate schema and update Makefile.am

There where some missing in Makefile.am so adding them in.
gsettings: Fixup the gschema files so they are valid

Replace underscore (_) with hyphen (-), lower case and hyphen are only valid
Add path where missing and add trailing slash (/).
Small corrections to the default values of keys

Todo:
1. Update code to reflect new key names with hyphen instead of
underscore.
2. Figure out what type of data is stored for Sdp. Currently made it a
string so it builds (but will for certain fail when used).
gsettings: Update all modules with the changed key names

Also updated all the ui/builder parts as some use the key
to pull in the correct gtk object.
gsettings: Remove org.blueman.pppsupport schema

It is a duplicate of org.blueman.gsmsettings.
gsettings: Add base keys to Constants.py
gsettings: Update .gitignore with *.gschema.valid

These are generated by gsettings and should be ignored.
gsettings: Restructure gschema files

 * Add new list keys to track gsm (apn) and device (netusage) by address.
 * Add plugin gschemas as childs.
 * Move org.blueman keys to org.blueman.general".
 * Add two keys to determine the dhcp handler.
 * Add plugin-list key to org.blueman.general.
gsettings: Initial port to GSettings

 * Replace most Config objects to Gio.Settings
 * Add relocatable schema path to Constants.py
 * Remove checks for None as this is not true anymore.
 * Bind settings to Gtk objects (not complete)

Todo:
 * The service window was ported but it broke.
 * Test and complete schemas with relocatable schemas
 * Update plugin framework to use plugin-list in org.blueman.general
 * Eveything I forgot and have not tested
 * In blueman-manager fix latest-last sort option
 * Remove config plugin completely
gsettings: Fix schema id and path for network gschema.
gsettings: Correct key type and description for org.blueman.sdp gschema.
gsettings: Set a default height.
gsettings: Fix some of my sillyness in efb349f586d228b4f61c7292eea30b1f9e2ebb12
GSettings: force GSettings Always all other config backends dropped
* Totally Drop main/Config.py option for configuration plugins
* If GSettings won't load then exit with failure
* Gio.Settings must be used directly by all modules
* WIP: Converting Individual Plugins away from PluginManager Storage system
* WIP: ConfigurablePlugin.py Merge with existing plugins