Major release to support TAXII 2.1
- #116 MemoryBackend enhancement to allow spec_version auto filtering
- #117 MongoDB document structure and pipeline change (breaking change)
- #119 Update test suite to prevent errors in MongoDB causing inconsistent behavior in requests
- #120 MemoryBackend update to default filter behavior when not provided in request
- #126 Fix stability issues with inconsistent behavior in requests (mainly affecting old Python versions)
- #127 Dropped support for Python 2.7, and 3.4 and Travis CI testing