Improve cwltest to handle keyboard interrupt.  Now exit code 0 when there are unsupported features but no failures.
Improve cwltest to handle keyboard interrupt.  Now exit code 0 when there are
unsupported features but no failures.

chapmanb/cwltool,dleehr/cwltool,chapmanb/cwltool,dleehr/cwltool,chapmanb/cwltool,dleehr/cwltool,jeremiahsavage/cwltool,jeremiahsavage/cwltool,common-workflow-language/cwltool,SciDAP/cwltool,common-workflow-language/cwltool,jeremiahsavage/cwltool,common-workflow-language/cwltool,SciDAP/cwltool,jeremiahsavage/cwltool,chapmanb/cwltool,SciDAP/cwltool,dleehr/cwltool,SciDAP/cwltool