Fix GitLab snippet export

The snippet export broke due to two reasons.
First of all, the request to GitLab fail in the
default configuration due to the CSP not being
set properly. This commit adds the configured
GitLab base url to the connect-src directives.
The second problem is a change in the GitLab API
spec. Instead of `code` and `file_name` the
GitLab API now requires an `files` array with
`content` and `file_path` entries per snippet.

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

test/csp.js

@@ -29,6 +29,9 @@ describe('Content security policies', function () {
       },
       dropbox: {
         appKey: undefined
+      },
+      gitlab: {
+        baseURL: undefined
       }
     }
   })