downcase http_method in pageview for version compatibility

in rails 3, request.method returns "POST" but in
rails 2, the result is "post".

Change-Id: Ia751b4db5f516bd3e62f15215d7918465fd7c418
Reviewed-on: https://gerrit.instructure.com/28543
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Anthus Williams <awilliams@instructure.com>
Product-Review: Anthus Williams <awilliams@instructure.com>
QA-Review: Anthus Williams <awilliams@instructure.com>