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.
Merge branch 'facebook-sdk-master' into facebook_merge

Conflicts:
	samples/FriendPickerSample/FriendPickerSample.xcodeproj/project.pbxproj
	samples/FriendPickerSample/FriendPickerSample/FPAppDelegate.m
	samples/GraphApiSample/GraphApiSample.xcodeproj/project.pbxproj
	samples/HelloFacebookSample/HelloFacebookSample.xcodeproj/project.pbxproj
	samples/HelloFacebookSample/HelloFacebookSample/HFViewController.m
	samples/HelloFacebookSample/HelloFacebookSample/en.lproj/HFViewController_iPad.xib
	samples/HelloFacebookSample/HelloFacebookSample/en.lproj/HFViewController_iPhone.xib
	samples/PlacePickerSample/PlacePickerSample.xcodeproj/project.pbxproj
	samples/PlacePickerSample/PlacePickerSample/PPAppDelegate.m
	samples/PlacePickerSample/PlacePickerSample/en.lproj/PPViewController_iPad.xib
	samples/PlacePickerSample/PlacePickerSample/en.lproj/PPViewController_iPhone.xib
	samples/ProfilePictureSample/ProfilePictureSample.xcodeproj/project.pbxproj
	samples/ProfilePictureSample/ProfilePictureSample/PPAppDelegate.m
	samples/ProfilePictureSample/ProfilePictureSample/ProfilePictureSample-Info.plist
	samples/ProfilePictureSample/ProfilePictureSample/en.lproj/PPViewController_iPad.xib
	samples/ProfilePictureSample/ProfilePictureSample/en.lproj/PPViewController_iPhone.xib
	samples/RPSSample/RPSSample.xcodeproj/project.pbxproj
	samples/RPSSample/RPSSample/en.lproj/RPSGameViewController_iPad.xib
	samples/RPSSample/RPSSample/en.lproj/RPSGameViewController_iPhone.xib
	samples/Scrumptious/Scrumptious.xcodeproj/project.pbxproj
	samples/Scrumptious/scrumptious/SCAppDelegate.m
	samples/Scrumptious/scrumptious/SCViewController.m
	samples/SessionLoginSample/SessionLoginSample.xcodeproj/project.pbxproj
	samples/SwitchUserSample/SwitchUserSample.xcodeproj/project.pbxproj
	samples/SwitchUserSample/SwitchUserSample/SUAppDelegate.m
	samples/SwitchUserSample/SwitchUserSample/SUSettingsViewController_iPad.xib
	samples/SwitchUserSample/SwitchUserSample/SUSettingsViewController_iPhone.xib
	src/FBViewController.m
Update project file deployment target to iOS 7 for 64-bit builds.

Reviewed By: chrisp

Test Plan: Built via XCode 5.
Merge branch 'facebook-sdk-master' into facebook_merge
Merge branch 'facebook_merge'