Facebook iOS SDK 3.8

Summary:
     see https://developers.facebook.com/ios/change-log-3.x/

    Upgrading from 3.7
     https://developers.facebook.com/docs/ios/upgrading-from-3.7-to-3.8/

Reviewed By: chrisp

Test Plan: Release Testing.
Fix some namespace pollution in the static library.

This fixes namespace pollution, to prevent linker issues with apps and other
libraries with global symbols named eg. "kSDK".

Conflicts:
	src/FBLoginView.m
	src/FBRequestConnection.m

Conflicts:
	src/FBRequestConnection.m
Prefix defaultResultsLimit and defaultRadius.

These symbols are exported into the static library, so make sure they're prefixed
to avoid namespace collisions.

Conflicts:
	src/FBPlacePickerViewController.m
Update src/FBDataDiskCache.m

'DISPATCH_QUEUE_PRIORITY_BACKGROUND' is not supported in iOS 4.0, only 5.0. It has been changed to 'DISPATCH_QUEUE_PRIORITY_LOW'
Add a search bar
Fix method name such that the analyzer doesn't throw

Conflicts:
	src/FBRequestConnection.m
Always renew the access token as we can never know if we're old or not
Make this at least work sanely on iOS 7

Conflicts:
	src/FBViewController.m
Update project files

Conflicts:
	src/facebook-ios-sdk.xcodeproj/project.pbxproj
Let's not do this. We renew anyway and that will, in general, fix the fact that there was no error but also no token.