We have requests for OpenDAP endpoints for NMME, CORDEX and other open datasets. We're not able to capture metrics requests for these requests.

Acceptance Criteria:

Include file_download metrics capture for OpenDAP requests (similarly to the NetCDFSubSet metrics handling).
Differentiate OpenDAP subset requests from NCSS subset requests (by type)

Here is an example CORDEX dataset with OpenDAP (and NCSS) service enabled:
  http://tds.ucar.edu/thredds/catalog/esgcet/126/cordex.kddm-livneh.NAM-22i.day.RegCM4.GFDL-ESM2M.hist.prec.v20170419.html?dataset=cordex.kddm-livneh.NAM-22i.day.RegCM4.GFDL-ESM2M.hist.prec.v20170419.prec.hist.GFDL-ESM2M.RegCM4.day.NAM-22i.kddm-livneh.nc