Bump to version 1.6.0

Bump Bamboo's version to 1.6.0. See Changelog for changes.

Bump version to 1.5.0 (beam-community#533)

Update version and changelog for version 1.5.0

Bump version to 1.4.0 (beam-community#516)

Update version and changelog for version 1.4.0.

Update version and changelog for version 1.3.0 (beam-community#494)

Bump version to 1.2.0

Update ex_doc

Mix format all the files

Update ExMachina 2.1

Release 0.8.0