Adding HA related changes.

Adding HA specific files. HA configuration data is stored in
cfe_internal/ha/ha_info.json.
Share keys between hubs and update policy_server.dat.
Copy hubs' keys to clients.
Disable HA by default.
Change the way client is updating policy_hub.dat content so that
right now it will be updated based on master hub IP placed in master_hub.dat.
Add separate directory where all hubs keys will be copied so that
client will be able to upload all hubs keys.
Add: Get unified list of hub SHAs.
Disable PostgreSQL maintenance policy to be run on slave hub.
Kill runalerts script on slave and make sure is working ONLY on master.
Synchronize PHP configuration files between master and slave.
Merge pull request #314 from pasinskim/ha_bish2

HA related changes