v2.3.3 -> v2.3.4

Features

• c105495 travis: add codecov

Fixes

• 4c72d59 codecov: add test-cover target

Maintenance

• 9d496b4 Dockerfile: update deis/base to 0.3.5
• d230c2b Makefile: update deis/go-dev to 0.20.0