alarm: Per user setting to disable ssl verify

This allows the user to disable ssl verification via a query string
parameter in the action url.

example of action:
 https://unstrusted-ssl-host/?ceilometer-alarm-ssl-verify=0

Change-Id: I12294aa191ff4dfa5adaf2e24419bdfca70e8726
Blueprint: alarm-notifier
Merge "alarm: Per user setting to disable ssl verify"