Added a method to disable IPv6 resolution.

Merge pull request facebookarchive#197 from facebook/gFosco.session-a…

…ppsecret-40dev

Updated visibility on FacebookSession::useAppSecretProof

updates including page tab handling, test changes

Tagging 4.0.6

Lots of updates.

Adding 4.0.4

Several updates

Several changes including ETag support, param and method fixes