Add 'restoreAnyVersion' attr for apps that want to restore "future" data

If a backup-participating app sets android:restoreAnyVersion="true" in its
manifest <application> tag, then its agent will be invoked for restore
even if the available dataset was created by a later version of the app
than is currently installed on the device.  This will not typically be
a problem for third party applications, since for them the installation
and initial data restore are tightly coupled, but it can cause serious
problems for applications which are both preinstalled on the system
partition and overridden by later updates.  The primary difficulty
that this new attribute addresses is this:

1. User buys a Nexus One, Market self-updates, and the user installs some apps.
At this point the backup data on the server may indicate that the version of
Market which originated its bookkeeping is newer than the stock N1 Market app.
2. User loses their phone, and buys a replacement N1.  At setup time, Market
has not yet had a chance to self-update, so when the restore comes in, it's
tagged as being from "the future" and so the restore is refused.  No apps get
reinstalled.

Bug: 2442127
Change-Id: I076a9553dc613e5c3189350e778315718ed1ed2b