Add missing quota flags in the config file sample

l3 extensions don't set quota flags in the config sample file
etc/neutron.conf.
Quota is unlimited if its value is minus and not only if it's -1.

Closes-Bug: #1250574
Change-Id: I76c8d1e2676d4e9b0feeed6e504e759fe736a0db
Fix NoSuchOptError in lbaas agent test

Option 'periodic_interval' doesn't exist when using testtools
to test lbaas agent, fix this by adding a mock object.

Change-Id: I5ef02d6fa154ea7a18ca77d02a2704b7e3990c3b
Closes-Bug: #1264260
Merge "Fix NoSuchOptError in lbaas agent test"
Merge "Add missing quota flags in the config file sample"