Ensure we don't access the net when building docs

(Note, this has not been sent upstream)

Change-Id: I9d02fb4053a8106672aded1614a2850e21603eb2
remove runtime dep on python-pbr

Change-Id: I6f247f64c561d49c13e3c2f67401fe150b6d47b6
Revert "Replace oslo.sphinx with oslosphinx"

This reverts commit c926216a9bd64d5cdd9731bd34e03613940d32e9.

Conflicts:
	test-requirements.txt
Move notification point to a better place

Follow-up for I80f325c9be9c171c2dc8d5526570bf64f0f87c78
"notify calling process we are ready to serve"

Xavier Queralt found issue with sending readiness notification from inside
run_service: it returns premature OK in case of multiple service endpoints
in one systemd service like nova-api which by default provides osapi, ec2 and
metadata services.

Instead, send readiness notification before entering wait loop for each
Launcher type.

Change-Id: I69bf10f353f5fecaaf89e537c2d3c46b73e39d36
Implements: blueprint service-readiness