Fix Hellofacebook sample to disable "status update" after a failed post action

Summary: depending on the FB session the buttons are either enabled or disabled after a failed post

Test Plan:
1. installed the app
2. logged in using fb connect
3. gave the permissions
4. posted to the test account
5. on the web browser deleted the sample app from fb account settings
6. came back to the app and clicked on the post status
7. error was thrown
8. then the buttons are disabled (this was not the case before)

1. after the previous step logged back in again
2. tested that all the buttons were enabled
3. repeated the above steps for post photo and pick friend buttosn

Reviewers: chrisp, akash

Reviewed By: chrisp

CC: vmehta

Differential Revision: https://phabricator.fb.com/D596426

Task ID: 1782510
updates
bug fixes
weird
Merge branch 'master' of https://github.com/facebook/facebook-ios-sdk

Conflicts:
	samples/Scrumptious/scrumptious/SCLoginViewController.xib
	src/facebook-ios-sdk.xcodeproj/project.pbxproj
	src/facebook-ios-sdk.xcodeproj/xcshareddata/xcschemes/facebook-ios-sdk-tests.xcscheme
	src/facebook-ios-sdk.xcodeproj/xcshareddata/xcschemes/facebook-ios-sdk.xcscheme
ignore paths
Removed Buildx Binaries
Update README.mdown
Update README.mdown
Update README.mdown
Update README.mdown
Update README.mdown
cleanup