Bug 984811

As is the case with a very old cartridge, if both
OPENSHIFT_POSTGRES_VERSION and OPENSHIFT_POSTGRESQL_VERSION do
not exist in postgresql/env directory, create one with '8.4'.

Hard coding this value should be OK, since 8.4 was the only supported
version of PostgreSQL for the cartridge this condition ever applies.
Merge pull request #3093 from BanzaiMan/stage_bz984811

Merged by openshift-bot