Keyguard: Set WIDGET_CATEGORY_KEYGUARD when AppWidgetHostView is created

Allows the default lockscreen widget to inherit the keyguard widget
host category.  Without this, only widgets added through
KeyguardActivityLauncher are assigned the correct
OPTION_APPWIDGET_HOST_CATEGORY.

Change-Id: Ic97818d85ca5f00da0ce43bb36006d66a6935363
Wipe and re-create database on downgrade.

Not a very common situation but should fix some errors that could
 arise from flashing an old ROM over a new one, without wiping data.

Change-Id: I27f2a00396761105987830921bb3f8cb339d2171