Update to dep 0.5

Description

dep 0.5 has been released, with some nice performance improvements. One thing is that

NOTE: your whole team will need to update at once to this new release, as it results in changes to the structure of Gopkg.lock that older versions of dep won't know how to work with.

Another new feature about dep is dep check which is a good way to check if our gokpkg.lock is in sync. Which we can use as a new step in out CI

Proposal

• Update to dep 0.5
• Add a new step in CI for dep check