v0.3.7

This release brings in a bunch of new functionality and bug fixes. Along with
basic maintenance like dependency updates and documentation improvements
(@ewildgoose).

Added

• Create, save, and extract tar files that contain metric data, see
  Mobius.Bundles and Mobius.make_bundle/2 for more information.
• Mobius.filter_metrics/3 to filter for desired metrics to enable the
  metrics to be consumed externally (@ewildgoose)
• Mobius.save/1 to manually save the state of the metric data for Mobius
  (@ewildgoose)
• :autosave_interval option to Mobius to enable a saving data at the given
  interval (@ewildgoose)

Fixes

• Unit conversion not working correctly (@ewildgoose)
• Error handling for when the :persistence_path is missing (@ewildgoose)
• Error handling when there is no data to plot (@ewildgoose)
• Crash when plotting an array of identical values (@ewildgoose)
• Correct off by one error when plotting (@ewildgoose)