[WIP] PostgreSQL 9.2 with SCL

Card online_runtime_157

PostgreSQL 9.2 is installed if available in a yum repository, and the application can be created and the postgresql 9.2 cartridge embedded.

PATH is correctly set, but `psql` on the gear's shell does not invoke the 9.2 binary for some reason:
```
[rack-fooooooooooo.dev.rhcloud.com 840813612036452727652352]\> psql
psql (8.4.13, server 9.2.4)
WARNING: psql version 8.4, server version 9.2.
         Some psql features might not work.
Type "help" for help.

rack=# 
```
On the other hand, `$(which psql)` works.