0.7.3 (linkerd#570)

Update CHANGES and bump version to 0.7.2 (linkerd#559)

Prep 0.7.1 release (linkerd#543)

Prep for 0.7.0 release (linkerd#506)

Bump head version to 0.6.0 (linkerd#442)

Bump head to 0.5.0 (linkerd#386)

* Bump head to 0.5.0

Bump version to 0.4.0. (linkerd#351)

Bump head version to 0.3.1. (linkerd#282)

Merge pull request linkerd#214 from BuoyantIO/greg/0.3.0-updates

Update headVersion to 0.3.0.

Merge pull request linkerd#161 from BuoyantIO/alex/disable-thrift-upg…

…rade

Allow control over thrift protocol upgrade