add relation joined hook with bogus service endpoint
Add initial attempt at setting relation info for new service. Does not work because keystone charm has hardcoded list of services it accepts relation info from.
use same name everywhere: glance-simplestreams-sync
fix error in traversing config json
bail cleanly when conf file is written with null values (likely before id relation is completed)
temporarily use 'oxygen' as a service name to get info from keystone
pass cloud image keyring to read_signed
Merge pull request #1 from mikemccracken/add-id-relation-joined

Add id relation joined