* Updated 'variables' -> 'variable_source_uuid' to type 'uuid' and removed the 'not null' constraint.
* Updated Database->insert_or_update_variables() to check/update 'variables_source_table' and 'variables_source_uuid'.
* Created the 'trusts' database table which will, when done, tell anvil-daemon which users@machines to trust (setup passwordkess SSH).
* Created (but not finished) System->manage_authorized_keys() and moved the logic over to it from anvil-daemon.
* Changed the host types "dashboard" to "striker".
* Moved the following methods from 'System' to 'Get';
** System->get_host_type to Get->host_type
** System->get_bridges to Get->bridges
** System->get_free_memory to Get->free_memory
** System->get_os_type to Get->os_type
** System->get_uptime to Get->uptime
* Updated striker to include the host_uuid for the 'node1', 'node2' and (if chosen) 'dr1' when running a job manifest.
Signed-off-by: Digimer <digimer@alteeve.ca>