Don't blow up on missing settings

Gruntfile.coffee

@@ -88,7 +88,7 @@ module.exports = (grunt) ->
 
 		shell:
 			migrate:
-				command: "./node_modules/east/bin/east migrate --adapter east-mongo --url #{settings.mongo.url}"
+				command: "./node_modules/east/bin/east migrate --adapter east-mongo --url #{settings?.mongo?.url}"
 
 		availabletasks:
 			tasks: