delete report attachments when rerunning

The html and resources were being deleted every time the report
generator runs but the attachments were not.  This has been corrected.
meta file in top level relative dir was not being auto
parallel execution mode implies batch

Parallel execution mode can only run in batch where each feature has its
own context.  In interactive mode the context is shared and therefore we
cannot run parallel mode interactively.  So now when you specify
parallel mode, batch mode is implicitly applied.