Exclude libs/*/migrations/* from run_tests.sh
Merge pull request #49 from sealevelresearch/add-observations-app

Add observations module with `Observation` model
Add convert_measurements to convert Measurements

Convert 15-minute EA measurements with Ordnance Datum into 1-minute
Observations based on Chart Datum for the location.

https://www.pivotaltracker.com/story/show/76127328

[Delivers #76127328]
Convert measurements every 10 minutes