Scrum timeline ui

PT story: https://www.pivotaltracker.com/story/show/78315784

- replaced some elements in scrum timeline to match WSO standards (is there a standard???)
- replaced 'Events' link in navigation bar with a dropdown menu with links to `/events` and `/scrums`
- removed "Previous scrums" link from underneath round banners
- refactored some scenarios in `basic_layout.feature` 

http://wso-events.herokuapp.com/

![skarmavbild 2014-09-07 kl 16 45 21](https://cloud.githubusercontent.com/assets/5248170/4178595/b8f37c2c-369d-11e4-9602-b3295c97142c.png)

![skarmavbild 2014-09-07 kl 22 54 30](https://cloud.githubusercontent.com/assets/5248170/4179677/3a798aec-36d1-11e4-8d03-697cfface713.png)