[rackspace|databases] removed trailing stash from hard coded endpoints; added accept header
[rackspace] adding accept headers to block_storage, cdn, compute_v2, databases, identity, load_balancers, storage
Revert "[rackspace] adding accept headers to block_storage, cdn, compute_v2, databases, identity, load_balancers, storage"

This reverts commit e438f21e68c84e3685f3c6a1effc640c60f253c9.
Merge pull request #1615 from rackspace/db_fix

[rackspace] Fixed DB Service endpoints and added accept headers