Add gitlab issue integration

Hey Justin,

Thanks for the help getting me set up earlier today.

Attached is my gitlab integration. I tested it against a private installation of gitlab. It should also work with regular gitlab.com.

I had one problem. I was able to sync the tickets, but the procedure tracking ticket didn't show up during comply serve despite 2 tickets being synced locally. Any suggestions would be greatly appreciated.

Here's the synced ticket. Is it because I have an empty body?

{
    "ID": "2727",
    "Name": "test issue",
    "State": "open",
    "Body": "",
    "Attributes": {
        "procedure": true
    },
    "ClosedAt": null,
    "CreatedAt": "2018-07-05T23:27:43.927+03:00",
    "UpdatedAt": null
}

A comply.yml would look like this:

name: "Acme"
filePrefix: "Acme"
tickets:
  gitlab:
    domain: https://gitlab.example.com:443/ # or https://gitlab.com/
    token: token-here
    repo: full-slug/of-project

Apologies in advance for any faux pas. This is my first time playing with golang.

Proof of it working:

strongdm / comply

Add gitlab issue integration #51