General clarifications, correcting misstatement about needing XCode on OSX

Adding some clarifications based on installation problems that happened today in an effort to head off problems tomorrow.
Merge remote-tracking branch 'ahmadia/gh-pages' into gh-pages

* ahmadia/gh-pages:
  added Bill Howe credits
  added UW-Seattle July website
  Webpage for Tufts University June 3-4
Merge pull request #153 from katieirenec/patch-2

General clarifications, correcting misstatement about needing XCode
Modifying day 1 schedule to give more time for testing.
Updating USU schedule.
Updating installation instructions.
Adding links to David's files.
Updating Etherpad location.
Adding links to intro/OOP material.
Adding OOP slides.
Adding complete solution notebook for invperc.
Adding SQL/shell cheat sheets.
Adding links to Ethan's scripts/data for shell section.
Escaping underscores in filenames.
Adding Ethan's SQLite database.
Added Notre Dame SWC web site.
Update hipchat info.
Adding the bootcamp page for CMU. I copied the version from umass but significantly cleaned up the HTML and improved the installation section. I think at some point I will contribute some of this back to the new bootcamp templates in the bc repository.  Also updated with all the specifics for this bootcamp.
Merge pull request #174 from swcarpentry/2013-07-cmu-pages

Adding the bootcamp page for CMU
Updated etherpad links with nicer urls