Fixes some memory leaks associated with testing applied forces

Fixes some memory leaks associated with testing applied forces

Fixes memory leaks associated with the electric
field test. Implemented a done_commrec function.
There may be need for a done_domdec as well but
that falls outside the scope of this patch.

Change-Id: Ib86629bb7959b064b6ac3a57d4bb96e2dd3bfe94