Add gitlab CI support

ci_info.js

@@ -68,6 +68,13 @@ module.exports = {
         branch:           env.BUILDKITE_BRANCH,
         commit_sha:       env.BUILDKITE_COMMIT
       };
+    } else if (env.GITLAB_CI) {
+      return {
+        name:             "gitlab-ci",
+        build_identifier: env.CI_BUILD_ID,
+        branch:           env.CI_BUILD_REF_NAME,
+        commit_sha:       env.CI_BUILD_REF
+      };
     } else {
       return {};
     }

test/test.js

@@ -48,6 +48,7 @@ describe('ci_info', function() {
 
     beforeEach(function(){
       delete process.env['TRAVIS'];
+      delete process.env['CIRCLECI'];
     });
 
     afterEach(function(){
@@ -79,5 +80,11 @@ describe('ci_info', function() {
       assert.equal(ci.name, 'buildkite');
     });
 
+    it('should return gitlab-ci as name if process.env.GITLAB_CI is set', function() {
+      process.env.GITLAB_CI = 'true';
+
+      var ci = CiInfo.getInfo();
+      assert.equal(ci.name, 'gitlab-ci');
+    });
   });
 });