Removed configobj from test requirements

This module is not longer used by any code in the tree since
f164a60f15ea042b04b250ffc2001beda4f3e4bc.

Also removed a reference to the module from a README file.

Change-Id: I66c4935cb2e119bc96109416df7116d8c09e24e4
Merge "Removed configobj from test requirements"