Make path validation into a class method as self is never used
Make path validation into a class method as self is never used

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