Allow sharing of firewall rules and policies in policy.json

Updated policy for firewall_policy and firewall_rule to allow sharing
among tenants. Added a new firewall sharing rule to enable this.

Change-Id: I5d4d9f94fb3abffe4d1b03c46fd5b13a8a4a4f09
Fixes: bug #1217103
Ensure nullable=False for netid in packetfilters table

From the initial commit of NEC plugin, network_id of packetfilters
table is nullable=False, but in folsom_initial db migration script
nullable is set to True. This commit ensure nullable=False for
network_id in packetfilters table in any migration revision.

Change-Id: I2f1ebc16b57d8d6548255079c66d326d97fda5b6
Closes-Bug: #1229508
Imported Translations from Transifex

Change-Id: I7df8b25fbe78ee7181ff6448ad3fd24d1f64a2a9
Merge "Ensure nullable=False for netid in packetfilters table"
Merge "Imported Translations from Transifex"
Merge "Allow sharing of firewall rules and policies in policy.json"