Use call to report state when ovs_agent starts up

Make sure to report ovs_agent state when starting up, otherwise
ovs_agent start_time would not be updated and thus l2pop does
not send fdb entries.

Change-Id: Idd770a85a9eabff112d9613e75d8bb524020234a
Closes-Bug: #1347452
Access correct key for template name

When an exception occurs while loading the config agent driver, the
handler tries to log a message, but accesses the wrong key to get the
template name. This causes another exception, which masks the original
exception.

This change accesses the correct key and performs logging inside a
with block to (defensively) preserve the exception context.

Change-Id: I3991bc4c509bbd8d68f7a1c8c8314404f2e0eafa
Closes-Bug: #1368900
Merge "Access correct key for template name"
Merge "Use call to report state when ovs_agent starts up"
Merge branch 'master' of https://github.com/openstack/quantum