Support for debug build in Ant.

"ant debug" now automatically insert debuggable=true in the manifest.

Also cleaned up a lot of the Ant stuff (versioned Ant rules, support
for importing different rules files based on compatibility computation).

This is rendered moot with our new single aapt executable. The ant
rules will now evolve alongside aapt, and there will not be mismatch
between the two.

Change-Id: Iaf309f40e6ab4a0204dfbdb428cfb569bf5ca3b3
16 files changed