Changed config dir to ~/.openstack.

Also added config file const.
Deleted regions and services code that was Rackspace-specific.

Also updated tests to use new directory.
Removed Rackspace-specific code for services.
More changes needed for general openstack.

This is related to previous changes that removed regions/services that were
specific to Rackspace.
Automatically create openstack dir and config file.

(If they don't exist.)
Removed unused tests.

These were from the clj-rackspace times...
Merge pull request #29 from oubiwann/os-config-dir

Os config dir