graceful-shutdown: add graceful shutdown into compute

The following commit brings in oslo-incubator service.py which
includes calls to support graceful shutdown.  The common service
class has changed to handle signals and manage Services.  When
a signal is received the Services are stopped which in turn
waits on all child threads (Proxy callbacks) to complete.

The oslo-incubator commit hash that was used to update
nova was b5fba9e40d609d63b4dab9ca351f7e22e9d8b35b.

This allows long running commands to complete prior to killing
the process.  This change only works for SIGTERM and SIGINT
signals.

Unit test was added to verify parent stop method is called in
a shutdown condition.

Change-Id: I21a45862f491530523037632fd70c60cc0153c0a
Implements: blueprint graceful-shutdown
Fail quickly if file injection for boot volume

Previously if the user attempted file injection on a booted volume it
would fail and retry several times, which slowed down the instance
spawning.  Instead of attempting file injection, fail quickly, and
log a warning

Fix bug 1188543

Change-Id: I264540de736c2bcb92567826fe5ba672e1244ba2
Merge "graceful-shutdown: add graceful shutdown into compute"
Merge "Fail quickly if file injection for boot volume"
xenapi: post install scriptlet to rpm

A freshly installed XenServer requires some modifications in order to be
able to run OpenStack. Nova contains an rpm specification to create a
package with the dom0 plugins, however installing the rpm is not enough.
Some more actions need to be taken:
 - create /images, link to a directory within the local SR
 - setup an ssh keypair, and authenticate it with the host
This change adds a post script to the nova plugins rpm spec file, so
by installing the rpm on a XenServer, it is ready to run OpenStack, no
further manual actions needed.

Change-Id: Id57e3a3ab2782550468c6aa4c01059ceb7cc81ab