Bug fix on update account.

When a user updates his account settings (in /home) there was a bug which destroyed the "session.user".

**Fix**
Use accounts.findAndModify instead of accounts.save because findAndModify is like save, but it also gives the updated document to your callback.

This way, the problem (from line 69 in router.js) is solved. (more infos here: [Node-MongoDB - Find and modify](https://github.com/mongodb/node-mongodb-native#find-and-modify) )

> Hope it helps.