clustermq 0.8.4

• Fix error for qsys$reusable when using n_jobs=0/local processing (#75)
• Scheduler-specific templates are deprecated. Use clustermq.template instead
• Allow option clustermq.defaults to fill default template values (#71)
• Errors in worker processing are now shut down cleanly (#67)
• Progress bar now shows estimated time remaining (#66)
• Progress bar now also shown when processing locally
• Memory summary now adds estimated memory of R session (#69)