Remove references to ruby-plsql gem

Removed the oracle gem

We don't connect to the oracle database.

If I need to search for something other than `plsql`, `oci`, or `oracle`, let me know.

AFTER: remove `ruby-plsql` from the rpmspec
@tenderlove This should be removed from our code base, but is this feature useful for Rails?  Is there an Oracle adapter in Rails?