Add an optional revisions method to all providers
Add an optional revisions method to all providers

icereval/waterbutler,kwierman/waterbutler,TomBaxter/waterbutler,CenterForOpenScience/waterbutler,felliott/waterbutler,Johnetordoff/waterbutler,rafaeldelucena/waterbutler,chrisseto/waterbutler,hmoco/waterbutler,cosenal/waterbutler,RCOSDP/waterbutler,rdhyee/waterbutler,Ghalko/waterbutler