GPII-247: Adding startActivityByPackageName method

This method can be used as a lifecycleManager action in order to launch
applications, identified by a well-known packageName.

To use this method for starting applications, your lifecycleManager
action block should look like it follows:

"lifecycleManager": {
    "start": [
        {
            "type": "gpii.androidActivityManager.startActivityByPackageName",
            "packageName": "com.package.name"
        }
    ]
}
GPII-247: Adding stopActivityByPackageName method

This method can be used as a lifecycleManager action in order to
stop applications, identified by a well-known packageName.

To use this method for stoping applications, your lifecycleManager
action block should look like it follows:

"lifecycleManager": {
    "stop": [
        {
            "type": "gpii.androidActivityManager.stopActivityByPackageName",
            "packageName": "com.package.name"
        }
    ]
}
GPII-247: Adding goToHomeScreen method

With this method we're adding a mechanism to get the user to the home
screen.
GPII-277: Adding get/set wrapper for Android.Settings

[Android.Settings wrapper]
  * These get/set methods provides us to get/set values from Android's
native Android.Settings. This wrappers can deal with settings from
Settings.System, Settings.Secure and Settings.Global

[More changes]
  * Move current AndroidFontSettings into a separate folder called
'AndroidFontSettings'
  * Add the new code into a folder called 'AndroidSettings'
GPII-277: Add stub for the new AndroidSettings class

[changes]
  * Adding Net_gpii_AndroidSettings new stub
  * Including a line for the new classes into makestubs.sh to generate
the new stub
GPII-277: Adding Settings Handler for Android's native settings

Including settings handler as js source code into activity_manager
node module. This settings handler can deal with System, Global and
Secure settings, and this should be specified in the options block of
the payload.
It follows the current policy about Settings Handlers, this is:
  * Provide both get/set methods
  * Receives the standard payload
  * Options block aren't included in the response payload
GPII-345: Adding a new and functional GPII Activity

This commit brings a new UI for the Android's GPII application activity.
Within the new design, we're providing some useful features to the user.

  * start/stop/kill the GPII instance of the device through the UI
  * Check the current status of GPII

Do do that, we've made the following changes:

  * Create the layout for the new UI
  * Include the Java code for the new UI
  * Add all the translatable stings into strings.xml
  * Add the logo of the GPII project
GPII-362: Updates the Ant build target to the Android 18 SDK.
GPII-368: Adds the ability to install the GPII apk in /system/app
Merge remote-tracking branch 'javihernandez/GPII-345'
GPII-345 Minor indent change.
Merge remote-tracking branch 'colinbdclark/GPII-368'
GPII-370: Adding translations for Spanish
GPII-370: Adding translations for German
GPII-370: Adding translations for Greek
Setting the right encoding for the Greek translations
Merge branch 'master' into GPII-277
GPII-277: Renaming nativesettings into androidSettings

* Rename module from nativesettings into androidSettings
* Moving back the java code to the original folder
* Updating ant.properties and makestubs.sh according to these changes
GPII-277: Updating platform/README.md according to latest changes
NOJIRA: Cleaning up prebuild.sh

Remove useless (and commented) source code from prebuild.sh