Update log message for add_host_to_aggregate

When add host to aggregates with availability zone, if the host
is already in one availability zone, then the host cannot be added
to another availability zone.

When user do above operation, nova api will report error message,
but the error message does not include blank space between
<availability zone> and zone name, also the error message include
two periods.

The fix was adding blank space and removes one period for the message.

Change-Id: I7307288be194d3ce6de05b77433bbe2626ae46d9
Closes-bug: #1237303
Fix a typo of tabstop

Only in nova/compute/manager.py, there is 'tabstop=6'. This change was
introduced at commit:2d0578c5. But this is an unintentional change.
This commit fix it to the same as others.

Change-Id: I5c4ffe354e2d37caa231de561ac257f23c6ab7d5
Remove unused scheduler rpcapi from compute api

Change-Id: I9af29b9daf21be369296d2b913019e4b80b18780
Merge "Update log message for add_host_to_aggregate"
Merge "Fix a typo of tabstop"
Merge "Remove unused scheduler rpcapi from compute api"