Use dep to manage dependencies

[vqhuy]

How to use dep (https://github.com/golang/dep)

1. Install dep: brew install dep
2. Download dependencies to vendor directory: dep ensure
3. Done

[vqhuy]

I don't think dep is supported in Travis as it's still an open issue (https://github.com/travis-ci/travis-ci/issues/8301).

[vqhuy]

I added a TODO to our Travis script so we don't forget this.

[masomel]

Great, thanks!

[corbym]

You can use dep with travis right now:

sudo: false
language: go
go:
  - 1.9.x
  - master
before_install:
  - go get -u github.com/golang/dep/cmd/dep
  - dep ensure
script:
  - go test
matrix:
  allow_failures:
    - go: master
  fast_finish: true
notifications:
  email: false
.. etc..