AT Command Injection v2 & RootTools

Totally re-wrote the AT Command Injection system using the RootTools library
which has helped simplify the system, this change should hopefully bring back
the same (if not better) level of functionality experienced with earlier alpha
releases.

Unable to test AT Commands on either of my devices but shell commands return expected results, so hopefully once tested AT Command execution can be
confirmed.

RootTools v3.5 - https://github.com/Stericson/RootTools
Added to project under libs directory, gradle build config updated but you may
need to check your IDE to confirm it is including RootTools.jar if you face
any problems.
Revert Notification Behaviour

Reverted notification behaviour so the idle (grey) icon is shown whilst the
app is running but not actively engaged in any task, normal (green) will
display when tracking or monitoring cell details and warning and alarm icons
will be displayed when triggered by changed LAC, femtocell detection etc.
Notification Update

Corrected the Cell Monitoring method so it will now correctly update the
notification icon based on the Cell Monitoring status.
Location Services (GPS) Handling

The prompting to enable GPS now better handles the users selection and
detects if GPS was actually activated when taken to the settings
fragment.

The activity itself forces a check as I cannot use the method
startActivityForResult from within the service, so whenever the activity
binds to the service or invokes onResume it will check the GPS location
service is running if Cell Tracking is enabled.

This also forces the user to either enable GPS or cancel the dialog box
which will leave the app in a desired state of operation.
Merge pull request #112 from xLaMbChOpSx/master

Various bugfixes, improvements and updates