Add changelog for 0.16 changes

bump version 0.15.14

bump version

v0.15.12 rerelease of v0.15.11

Version 0.15.11

Merge pull request #575 from burke/andrew-bump-version

Bump version to 0.15.10

Merge pull request #568 from stripe/andrew-ttyutils

Update vendored ttyutils and cut a new version

Bump version to 0.15.8

Version 0.15.7

Version 0.15.6