Deprecate DATABASE_TYPE and use_database

Select a database by adding it to ENABLED_SERVICE like all
of the other services.  This greatly simplifies using the lib/*
functions in places other than stack.sh

Change-Id: I967e44603b4d69d5d70e1a75a9938172ca434025
Fix create_userrc.sh private key hang

tools/create_userrc.sh hangs in a couple of mv commands now that
private keys are created with mode 400.  mv is prompting to
override the permissions, so let's just -f it all.

Change-Id: I8fbb24da6582edcff741653ffdf8bf683b79851a
Merge branch 'clean-ex' into dt-test
Merge branch 'database-service' into dt-test