Make Twitter and RSS widgets more compact

This should make it easier to shuffle these around on the homepage,
but it also tries to make the news look a little more prominent.
Extended overhaul of main page

- H2 slogan is updated based on Mo's pull request
- "What is Aeolus?" content spans full width; totally rewritten
- News and Twitter content sits below content
- Twitter widget colors now blend in with site color scheme
- 'For Developers' section is removed; it didn't make a lot of
   sense on the homepage, and conveyed little actual information.
Merge pull request #98 from n1zyy/homepage-revamp

Homepage revamp