Do not maintain internal cache in syncing project from keystone to contrail DB

[Hampapur Ajay]

An internal cache was maintained earlier for projects and domains
to optimize on keystone poll for adds.

Since we have effectively moved to add project/domain on demand,
there is nothing to be had by maintaining internal cache (with its
attendant invalidation/resyncingproblems). Instead read the project/domain
from contrail database on pre_<proj|domain>_read and sync only if not already present.

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/14715
Submitter: Hampapur Ajay (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Reviewed: https://review.opencontrail.org/14715
Committed: http://github.org/Juniper/contrail-controller/commit/f7f6b40f1758ea00d4df8b3679ba3821736a67c5
Submitter: Zuul
Branch: master

commit f7f6b40f1758ea00d4df8b3679ba3821736a67c5
Author: Hampapur Ajay <email address hidden>
Date: Thu Oct 29 13:16:40 2015 -0700

Do not consult internal cache in project/domain sync from keystone.

On pre_<project|domain>_read see if the object is present in contrail
database and sync it from keystone if not present.

Closes-Bug: #1510308
Change-Id: I10c7b0b715ffbb3de90a101ca2e7f632d732997f