Add support for CORs credentials/authorization
Add support for CORs credentials/authorization

     Send back Access-Control-Allow-Credentials as true to allow
     cookies to be sent cross domain.
     If CORS_ALLOW_ORIGIN is * (wildcard) match request origin as
     wildcards do not work with allow credentials

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