ENH: Move stations.csv into package

[KCollins]

Description

Right now the wavefig function pulls from a local file, stations.csv, which is in the notebooks directory. It would be better form to have the .csv file included as part of the python package.

Potential impact

This will help new users avoid errors.

Potential solution(s)

cf. https://stackoverflow.com/questions/25531476/is-it-possible-to-include-csv-file-as-part-of-python-package