nasapy 0.2.2 release

• An optional return_df parameter has been implemented in the listed functions below. When set
  as True, the resulting JSON data will be coerced into a pandas DataFrame to allow easier and more straightforward data analysis for those interested. Please see the individual function documentation for more information and examples.

  • fireballs
  • close_approach
  • nhats
  • sentry
  • scout

• General bug fixes

  • The sentry function should now operate correctly when passing a des or spk parameter.