Environment: add postgresql-devel to install list

Some of the pip scripts gave me an error before installing
postgresql-devel. So I'm adding it to the yum install list
Revert "Env: reset_ps1 function now with whoami"

This reverts commit a76f4bf98fb2d95976e614f95acbb2c351008788.

whoami is not needed if the user will always be vagrant