update CHANGELOG.md for 0.15.4

update CHANGELOG.md for 0.15.4

update CHANGELOG.md for 0.15.3

update changelog for 0.15.2

Bump version to 0.15.1; update CHANGELOG and version references

changelog for v0.15.0

update CHANGELOG.md for 0.14.2

update CHANGELOG.md for 0.14.1

update CHANGELOG.md for 0.14.0

update CHANGELOG.md for 0.13.4