Host aggregates panel.

On this panel, aggregates could be added, deleted and edited.
This patch takes the aggregates panel out of System Info and
puts it back in the main admin panel list, as now, aggregates
are not static information. The host can be associated to a
host aggregate on this panel as well.

Change-Id: I4ef2d87c33981db36d4ebd3de2f4841cdfa9dbfd
Closes-Bug: #1261932
Implements: blueprint manage-host-aggregates
Co-Authored-By: Santiago Baldassin <santiago.b.baldassin@intel.com>
Co-Authored-By: Alejandro Paredes <alejandro.e.paredes@intel.com>
Merge "Host aggregates panel."