Add project submission

##### User-facing project submission (issue #107) that:
+ Creates a project submission form
+ Links it to the home page

*Project submission form*
![image](https://f.cloud.github.com/assets/2766324/1822815/a70bbeaa-716a-11e3-98f3-6b914bc099f2.png)

##### Potential improvements:
- [ ] Adjust submission form to allow existing organizations to submit new projects
- [ ] Create helper function to parse github urls, allowing for a more intuitive form
- [ ] Allow an organization to submit multiple projects (a + button to add additional form fields?)
- [ ] Prettify the form itself, possibly by combining Organization & contact details onto one line each?
- [ ] Create site-wide CSS to highlight flash notices & cleanly post form errors