Fix service API and cells

The move to the object model broke the service API when used together
with cells. The underlying problem is how cells will overload the id
field with a cell path to uniquely identify each service in each cell.

Changing the id to a string would defeat the purpose of the object model
so this patch uses a proxy to modify the id on access to make the
difference transparent to the API.

Change-Id: I165b5d64b0c1556511eb02d179ca9fc6f101c008
Closes-bug: 1251043
Add nova.conf.sample to gitignore

Now that we aren't storing this in tree and are recommending people
generate it locally add nova.conf.sample to .gitignore.

Change-Id: I0727c7552fead5a201116f9c2c6510fec3b92cd6
Merge "Fix service API and cells"
Merge "Add nova.conf.sample to gitignore"