Remove double requirement.

Fixes #24

When updating an analysis, the user was receiving 405 error codes.  This
stemmed from the fact that the _update code invoked required the browser
send a POST request, but then outsourced to another function that
required a GET request.  (@require_POST vs @require_GET)  No good, and
now fixed.

Signed-off-by: Kevin Hunter <hunteke@earlham.edu>