Add "Code Later" option on Explore Projects page

![CodeMontageCodeLater](https://f.cloud.github.com/assets/226228/421505/567d667a-ad0a-11e2-8d2b-0616386985e9.jpg)
![CodeMontage - Calendar](https://f.cloud.github.com/assets/226228/421518/96cd37fa-ad0a-11e2-9d3e-55376fbbebba.jpg)