Move scripts to the bottom of the page

Script tags should be the last thing on the page for performance related
reasons. We should also send as few scripts as possible.

To that end I have:

- Moved the application and analytic scripts to the bottom of the page.
- Meged the application and analytics code so its a single download.
- Moved the print detection analytics code into a JS file and included
  it with the analytics code

I have confirmed that custom analytics variables added with slimmer still work with this change. This pull request will want to be merged after people have updated to the new slimmer (when this pull request is merged alphagov/slimmer#41) due to this moving where jQuery is included in the page to possibly after where people expect it to exist.

The only other note is that while I would have liked to merge all of the inline analytics code into one block I have left it as two due to the way slimmer adds extra code to the first block, which needs to be there before the second is executed.