tools: notifier - add aditional validation

Check for valid email (simple @ validation)
Check for valid port number (1-65536)
Check for true or false in HTML_MESSAGE_FORMAT

Change-Id: Id97cb5bd1903991717e653cf2ca4ca16f362f8e6
Bug-Url: https://bugzilla.redhat.com/883417
Signed-off-by: Noam Slomianko <nslomian@redhat.com>