put {"_id":"test"} when "test" already exists -> conflicts
revisions can pass the checkRevisionFormat function now

before: putAttachment('docid/attmt','rev','data','mimetype',callbacks);
now:    putAttachment({id:'docid/attmt',rev:'rev',data:'data',mimetype:'mimetype'},callbacks);

Original authors: Sven Franck and Tristan Cavelier