Add missing catch blocks for migration from 1.1.1 to 1.2.0

Signed-off-by: Hugo Caloto <hcaloto@gmail.com>

lib/migrations/20150702001020-update-to-0_3_1.js

@@ -20,6 +20,12 @@ module.exports = {
         type: Sequelize.INTEGER,
         defaultValue: 0
       })
+    }).catch(function (error) {
+      if (error.message === "ER_DUP_FIELDNAME: Duplicate column name 'shortid'") {
+        console.log('Migration has already run… ignoring.')
+      } else {
+        throw error
+      }
     })
   },