[4.0] Fixed warnings when open_basedir directive set
Fixed long lived sessions forgetting the signed request
Merge pull request #186 from SammyK/fix-for-open_basedir-directive-4.0

[4.0] Fixed warnings when open_basedir directive set
Merge pull request #191 from SammyK/fix-long-lived-session-forgets-signed-request

Fixed long lived sessions forgetting the signed request
Removed GET processing from CanvasLoginHelper.
Merge pull request #195 from facebook/gFosco.canvasGET-40dev

Removed GET processing from CanvasLoginHelper.
Updated visibility on FacebookSession::useAppSecretProof
Merge pull request #197 from facebook/gFosco.session-appsecret-40dev

Updated visibility on FacebookSession::useAppSecretProof