Remove 'Registration is open' and enhance 'sign up for next time'

... on home page. Closes #56.
Add instructor informational page.
Fix Microsoft URL
Add Lydia's bio
Remove Samantha due to scheduling issues.
Merge pull request #57 from railsbridge-boston/reg-closed

Remove 'Registration is open' and enhance 'sign up for next time'
Randomize sponsors
Replace Annkissam logo.