Fixed incorrect domain matching for ZERO

Replaced "\.([a-zA-Z0-9-]+)\.org" with "\.wikipedia\." host matching
because Zero is currently enabled only on wikipedia.

This could have been the reason why analytics was showing higher numbers:
  Non wikipedia traffic was marked as ZERO even though it wasn't.

Not checking for .org at the end allows the same code to run on betalabs.

Change-Id: I1359a78d7b3fc32637923bff7fb964e6c16ed1d0