Feature/ncei extraction

[collijk]

This PR adds in a script to extract the NCEI climate station data. Because it's the first script it also sets up several infrastructure pieces:

• This PR adds two entry points (ie command line tools that get installed when you install this package):
  • cdtask: This entry point will be used to run individual workflow tasks. This is super useful for debugging
  • cdrun: This entry point will launch parallel jobs using jobmon. Jobmon will invoke cdtask with appropriate arguments.
• It adds an automatic discovery loop in the climate_downscale.cli so new commands are added automatically as long as they're appropriately imported. RUNNERS (ie cdrun subcommands) and TASK_RUNNERS (ie cdtask subcommands) are set up in climate_downscale.extract.
• It adds a ClimateDownscaleData object that will parse the local directory structure and eventually load and save data. This will make it super easy to move around the data/modeling root.
• Starts a README for climate data extractions

In addition, the actual extraction script is included.