Add lib-file support to Android

lib-file does not work in platforms other than Blackberry.
This patch adds lib-file support to Android.

Without this patch the plugman install.js crashes because handler["lib-file"] is undefined.

If you want to test this create a plugin with an <platform name="android"> section and  a lib-file sub-element.
e.g. 
<lib-file src="libs/org.simalliance.openmobileapi.v2.0.2.jar" arch="device"/>

"arch" is ignored because it is not relevant for Android.

With this patch all files listed in lib-file elements are copies to projectdir/lib/ where the Android build tools expect external libraries.