Follow gerrit's changes in Gitweb class names

Gerrit core moved GitWebConfig into a different package in

  7023f47c4bb359ceef667b00a481531193e46b19

and the class names were changed to use consistent lowercase in

  a3d67882125065c86ae55ccbb45e36d2ca6e453e

. We follow those moves to allow compiling against gerrit's master.

Bug: Issue 3431
Change-Id: If656bbb9822d0118d9124ac469e5f6754bc79575