Update version to 0.7.1 in setup.py

Arigdon usgs avg docs

ObsPy/NumPy have a bug related to masked arrays that this small
change works around by forcing gaps to be filled by NaNs, even
during intermediate processing.

- simplified default assignments in AverageAlgorithm.process() as per
  @jmfee-usgs' recommendation
- inserted command-line configuration logic to deal with location
  code

Merge branch 'AvgDocs' of https://github.com/arigdon-usgs/geomag-algorithms into arigdon-usgs-AvgDocs

moved ipynb to .gitignore, updated docs a little, cleaned up and reorganized AvgAlgorithm.py(); got rid of get_trace instead of removing, a new way of setting the latitude corrections with a dictionary (in process so that it works the same for command line vs script performance), set observatories to be more pythonic

created an interactive python notebook for average algorithm. Removed redundant metadata and added better functionality for scaling and observatory checks

Merge streams fix

Changed sampling_rate to delta in __create_trace() so that the start and endtimes are calculated correctly

Fixed some linting errors and made the merge_streams() code cleaner as well as added more unit testing

Cleaned up merge_stream(), takes empty channels out at the beginning and adds them in before the merge() function

Reset the Timeseries Utility to the master. The changes will be introduced in a separate pull request

Fixed npts issues in create missing and channels as well as a unit test. Also cleaned up the unit test code for syntax and linting.

Fixed logic in XYZ test under unneccessary channels

Added unit tests to XYZAlgorithm_test.py for limited channels as well as gaps in unneccesary channels

Cleaned up channel initialization in XYZalgorithm and calls to get_required_channels() in algorithm.py