Add an option to change the device hostname (1/2).

This adds an option to modify the device hostname used
in ip resolution. This is useful when connecting to the
android device in a dynamic dhcp environment.

Change-Id: I44e4771f4415a32fe66867d4dd90f1ad138341e1

Conflicts:
	core/java/android/provider/Settings.java
	services/java/com/android/server/ConnectivityService.java

 Author:    Alex Avance <aravance@gmail.com>
 On branch jb-4.2
 Changes to be committed:
	new file:   core/java/android/provider/Settings.java
	new file:   services/java/com/android/server/ConnectivityService.java