Minor verbiage changes in blinkdb.md.
Merge branch 'ampcamp3'

Conflicts:
	ampcamp/blinkdb.md
remove _site from version control and add it to .gitignore
make links under each day subheading on index page go to the appropriate section in the exercises (and label the link to the project webpages explicitely). also make the styling of the drop down/up nav menus more obvious in the header and ffooter so people might figure out they can click to see other nav items.
add explanation of the dropdown menu for nav to intro
Differentiate current page in drop down nav. Tweak subheaders on intro page: "Day [1|2]" -> "Day [1|2] Exercises".
Merge branch 'master' into ampcamp3