fixed responsiveness

Changed header for site from Generate to Create

I did a search on google insights to find out what people who are
searching gitignore files are looking for.  The highest words were
create, then make, and then generate.  This prompted me to change all of
the Genearte words to Create in order to help people find gitignore.io
easier.  It should also boost the rankings which will help as well.

Added image for card SEO

Added SEO for twitter, facebook, and googleplus cards

Added fixes to twitter and facebook cards