test_vm Cheffile - move postgresql cookbook to more up-to-date version
(It's still on a custom repo until COOK-4095 is fixed upstream)
Vagrantfile - simplify postgresql config (the defaults are the same)
test_vm - replace chef_gem "pg"  with postgres::ruby
test_vm - regenerate Cheffile.lock after postgres cookbook url change
test_vm - bump up postgres version to 9.3
ORACLE.md - put a note about the Oracle auto-provisioning