Fix comparison of MW internal links

We need to normalise titles so 'user:foo_bar' == 'User:Foo bar', and
we also need to some HTML attribute removal as links from Parsoid
will have href and rel set (again, this should be fixed in by Parsoid
when the do the merging at their end).

Bug: 49985
Change-Id: I5fb5bfc69c344ca4ce4803d7b6116074648a8d7e
Merge "Fix comparison of MW internal links"