AAPT: Add flag to disable versioning of vector related XML

AAPT automatically versions XML files according to the SDK level
in which their attributes were introduced. Support libraries
know how to handle resources built against newer SDKs, so offer
the option to disable some of the automatic versioning, namely
vectors.

Bug:19336994
Change-Id: I9f9d0ae8f2a0c28404f82e27de416f80e38493c9