Introduce vendor directory into the repo

[seemethere]

Was trying to build the CLI from the source directory and I could not,
this re-adds the vendor directory so we can build the CLI from the
source repository instead of having to dep ensure everytime

ping @ilikebits

[seemethere]

Not really seeing why the tests are failing?

[elldritch]

The tests are failing because our tests have a dependency on the FOSSA API, which requires us to pass a secret API key to the tests. This is not passed to tests running on forked PR branches for security reasons. We should probably turn off the API tests for non-master commits.

I'm not sure that committing vendor is a best practice, and installing with go get -u github.com/fossas/fossa-cli/cmd/fossa works for me. What are the steps for reproducing your installation failure, and what are the arguments for checking in vendor? (The main argument I can think of against committing vendor is repository size.)

[seemethere]

@ilikebits Committing a vendor is standard practice for almost every golang project on Github.

See:

• kubernetes/kuberenetes
• moby/moby
• ethereum/go-ethereum
• containous/traefik
• gin-gonic/gin

What it allows you to do is not pollute your $GOPATH/src/ with dependencies from a go get -u

Even your CircleCI builds don't do a go get they do a dep ensure before running make. https://github.com/fossas/fossa-cli/blob/master/.circleci/config.yml#L25-L26