Remove jQuery ajax dependency from garden-o-matic

This introduces net.json() and net.xml() and replaces all appropriate uses of net.get() that depended on automatic behavior

BUG=

Review URL: https://codereview.chromium.org/165313003

git-svn-id: svn://svn.chromium.org/blink/trunk@167146 bbb929c8-8fbe-4397-9dbb-9b2b20218538