Add user feedback for front-end actions

[bjornarjatten]

• [x] When logged in/login failed
• [x] When registered/register failed
• [x] When followed/unfollowed
• [x] When message is posted
• [ ] When following a user, the page must re-render
• [ ] When unfollowing a user, the page must re-render
• [ ] When posting a message, the page must re-render
• [ ] More..?

[bjornarjatten]

Moving to next weeks focused work