Start extending to support GitLab authentication.

Add necessary dependency.
Add baseURL parameter for self-hosted GitLab
Add necessary require.
Add block for GitLab auth.
Fix typo
Update font-awesome dependency for GitLab icon.
Use a color closer to GitLab orange.
More direct TODO

lib/response.js

@@ -94,6 +94,7 @@ function showIndex(req, res, next) {
         facebook: config.facebook,
         twitter: config.twitter,
         github: config.github,
+        gitlab: config.gitlab,
         dropbox: config.dropbox,
     });
     res.write(content);
@@ -124,6 +125,7 @@ function responseHackMD(res, note) {
         facebook: config.facebook,
         twitter: config.twitter,
         github: config.github,
+        gitlab: config.gitlab,
         dropbox: config.dropbox,
     });
     var buf = html;