Remove client side logging

In Internet Explorer 9, console.log (and similar) do not support
`apply()`.

This commit makes client side logging a no-op because most logging
information that we care about is in the network tab of any good
browser.

In future, proper client side logging is something we may want
to do.
Merge pull request #788 from alphagov/fix-logging-ie9

Fix client-side logging in IE9