Mitreattack-python

- Added functionality to `MitreAttackData` to retrieve a list of Procedure Examples by technique. [172](https://github.com/mitre-attack/mitreattack-python/pull/172)
- Updated `navlayers` module to support Navigator version 5.0.0.

Fixes

- Fixed a layer comparison issue causing false warnings to appear during layer operations. [173](https://github.com/mitre-attack/mitreattack-python/issues/173).

Fixes

- Fix logic for finding deprecated ATT&CK objects in `changelog_helper.py`.

Fixes

- Update release information for ATT&CK 15.1... for real this time

Features