fix(nfs): now using the correct columns for datapoints
fixes https://github.com/BrightcoveOS/Diamond/issues/556

Change-Id: I3300feb4f319fffb77bba6f6d3fbf2d65bb75046
test(nfs): added fixtures to testcases

Change-Id: I82e7c4ceb2e4d87e24538612d76814c75562fec0
test(nfs): removing debugging

Change-Id: Ifb50e9271d5000a1e0d40766bc8c47ab0560b919
Merge pull request #637 from rtoma/nfs-fix

fix(nfs): collector now uses the correct columns for datapoints