Enable filter alarms by their type

Since type is a very important attribute for alarm object, it will be much
convenient to get alarms by certain type. This patch adds the 'alarm_type'
parameter to get_alarms interface to implement it.

End user can filter alarms by using 'type' filter.

NOTE: this patch changes the parameter 'type' to 'alarm_type' in
get_alarm_changes interface of storage module, to keep consistent with
get_alarm interface.

Change-Id: Ib81375028957490f3a114de7627bc4bcb20f3d77
Merge "Enable filter alarms by their type"