Add more variables to opsview_contact type

[dpeters]

Currently opsview_contact only supports the email variable. It should at least include all the default variables (rss_collapsed, rss_maximum_age, rss_maximum_items), along with pager, since it's a common one.

[dpeters]

Since these variables are open ended (any notification method can create new ones), it doesn't make sense to hard-code any variables into this.

Instead, #4 implements the variables property as a Hash of the variables:

opsview_contact { 'me':
  ...
  variables => { 'EMAIL' => 'me@example.com', 'PAGER' = '555-1234' }
  ...
}