updated bootstrap css stylesheet to 3.1.1 from content delivery network
fixed title in header meta-data, now set as Hack the Tower - London Hackday
updated hack the tower description to be a little more concise
updated hack the tower description to be a little more concise, again
wrapped description in a banner, aka the jumbotron
added http to url for united theme so it can be tested locally
moved hack the tower image into the jumbotron header, removing the need for seperate tags in a span row
moved the Salesforce sponsor banner to below the main banner, centering the banner using float.  The salesforce logo is managed by a style in the hackthetower CSS file
centering the website title - added an id to the title h1 tag and defined a style for the id in the hackthetower CSS
tweaking format of website title and heading text & image
converted span elements to grid using col-md-3
updated agenda from unordered list to descriptive list; updated comments to help identify sections of the website
added embedded Google map of Heron Tower; using a flexible container style in the hackthetower CSS
added embedded twitter showing latest tweets from HackTheTower; using twitter-timeline class and a JavaScript script included in the html file