Changes:
- Improve compatibility with cocotb 1.6
- AXI: Enable case insensitive matching (19, 29) [Aaron Holtzman, c-93]
- Avalon: Don't sample in the postponed region (26) [Greg Taylor]
- Move lock methods to base class by (23) [Todd Strader]
**Full Changelog**: https://github.com/cocotb/cocotb-bus/compare/v0.1.1...v0.2.0