Bug 983190

Publish $OPENSHIFT_POSTGRESQL_VERSION to all gears, and depending on
whether `scl` is available, set up the `psql()` wrapper in `rhcsh`
appropriately.
Fix up psql command usage in cucumber tests

With the previous commit, the 'psql' invocation should be correct.

Fixes runtime_extended tests for postgres.
Ignore STDERR while checking for 'scl'
Merge pull request #3059 from BanzaiMan/dev/hasari/bz983190

Merged by openshift-bot