Merge pull request #15 from mhemesath/master

Update site design
Minor fixes:

- Fix typo on 'text-centered' class for the location div
- Move the 'about' id to the main tag so #about moves to the very top of the page
Revert #about id change -- invalid HTML!
Change the main banner image (fixes #12)
Change the standout text from blue to dark grey
Add additional information on the call for papers
Cleaned up mobile