Rename all badges with git-lab to gitlab

I deployed #865
Then we reverted that change
#876

So the migrations that were reverted have been run on production :(
These new migrations are idempontent so shouldn't affect anyone who
*doesn't* have the reverted migrations...

Author: carols10cents

migrations/20170711193021_rerename_gitlab/down.sql

@@ -0,0 +1 @@
+UPDATE badges SET badge_type = replace(badge_type, 'gitlab', 'git-lab');

migrations/20170711193021_rerename_gitlab/up.sql

@@ -0,0 +1 @@
+UPDATE badges SET badge_type = replace(badge_type, 'git-lab', 'gitlab');