Adding missing shebangs to scripts
Add missing header comment to osx.sh
Adding empty rmv user 'db' config file

This is the primary rvm user config file. There are no user-specific
settings being used and rbenv is currently the preferred ruby version /
environment tool, but including .rvm here because it is still installed
and there are other rvm-specific settings elsewhere in these dotfiles.
This also provides easier, clearer access to the overall rvm
configuration, just like with rbenv, since everything is now contained
within the .dotfiles directory.