Allow use of lowercase section names in conf files

Fixes bug #1189889

oslo.config-1.2.0 normalizes section names in config files to lowercase.
This means that simply by upgrading to oslo.config-1.2.0, users will now
be able to do e.g.

  [default_servicetype]
  description = ...
  service_definition = ...

Change the default config files to make it clear we recommend the use of
lowercase section names.

Note, the use of an alpha tarball of oslo.config requires pbr>=0.5.15
but we already require >=0.5.16.

DocImpact

Change-Id: Ia47fb3d168da71d3221b25979f8c9257d70dd64d
Reference default_servicetype group in lowercase

Now that we require oslo-config-1.2.0, we can start referencing group
names as lowercase. Let's start with the default_servicetype group.

We do this simply by changing the case of the group name passed to
register_opt():

  -cfg.CONF.register_opts(..., 'DEFAULT_SERVICETYPE')
  +cfg.CONF.register_opts(..., 'default_servicetype')

and this means that all options in the group now need to be referenced
using the lowercase group name i.e.

  -svc_defs = cfg.CONF.DEFAULT_SERVICETYPE.service_definition
  +svc_defs = cfg.CONF.default_servicetype.service_definition

Note however, users can still use the uppercase section name for
backwards compatibility.

When we last attempted to do this, oslo.config-1.2.0 wasn't actually
being installed correctly so add a unit test which verifies that both
uppercase and lowercase section names work.

Change-Id: I9357397f39d8f7d0d4f445b78aae5665c7ece3d4
Fix TestNecAgentMain not to call sys.exit()

test_main() was calling sys.exit() killing test running
and not allowing tests to complete in a proper way.

Drop explicit sys.exit() call from net agent's main() and
fix outdated mocks in test_main().

Fixes bug #1192270

Change-Id: Iea8d5508f73eb9144e452de3305f2dec4c2a319c
Imported Translations from Transifex

Change-Id: Ic05603ef37a6be3f5482f5b268958eedf4a6eaa1
Merge "Allow use of lowercase section names in conf files"
Merge "Reference default_servicetype group in lowercase"
Merge "Fix TestNecAgentMain not to call sys.exit()"