Bump up PostgreSQL memory parameters

Bug 1003445
Values are discussed in
https://bugzilla.redhat.com/show_bug.cgi?id=1003445#c1

Larger gears should allow even larger values, but further discussions
are necessary.

Values are lower on embedded cartridges.
Merge pull request #3547 from BanzaiMan/dev/hasari/bz1003445

Merged by openshift-bot