Updated bug with missing obs_var

Closes #83

See merge request !51

Merge branch '68-test-that-the-netcdf-s-produced-by-mapies-concatenate-to-work-correctly-with-ncview' into 'master'

Resolve "Test that the Netcdf's produced by Mapies - concatenate to work correctly with ncview"

See merge request !50

Resolve "Make sure viirs can work with SNPP"

Closes #79

See merge request !49

Resolve "[TROPOMI] Make the tool work with many types of data not just No2"

Closes #69

See merge request !48

Resolve "Averaging by frequency instead of monthly/yearly"

See merge request !47

Adding notebook example

See merge request !45

Resolve "Add a filter that is the minimum number of observations per grid cell to aggregate"

Closes #32

See merge request !44

Resolve "Update Gantt chart for 0.2"

Closes #66

See merge request !43

Resolve "Move plotting to a separate file and plotting object"

Closes #60

See merge request !42

updating time orig from hard coded value

See merge request !41

Resolve "Update of Logging"

Closes #38

See merge request !40

Resolve "Incorrect date in saved netcdf files"

Closes #64

See merge request !39

Update of readme

Closes #62

See merge request !38

Resolve "Update the Grids configuration"

See merge request !37