v1.005 breaking change: $wgTrustRoot to $wgOpenIDTrustRoot

Version bumped to 1.005, preparing for a move to 2.x.

This fixes a variable name which was not in conformity with the
other variable names. All global variables of the OpenID extension
start now with "$wgOpenID" .

This change is documented in a new file CHANGES, and further updates
to the Manual page will be done.

The fix prepares for a major change to version 2.x of the extension.

Change-Id: I7737a0cb3261053de0b65b716d55f89e4315d834