redirect logging to a file in call to RNA-Seq Toil pipeline

[wshands]

Redirect logging to a file in call to RNA-Seq Toil pipeline using --logfile= (to be added to wrapper.py) in toil-RNASeq so that log files that go to stdout are available during the run from dockstore. It seems now that running the pipeline from docstore_tool_runner results in non visible log information until cwltool creates cwltool.stdout.txt and cwltool.stderr.txt when the run completes. This will require adding the --logfile switch to the toil-rnaseq wrapper.py.

See http://toil.readthedocs.io/en/releases-3.7.x/cli.html#loggingref