Fix several folder picker bugs

* Fix a crash when the folder picker is loaded and the SDK becomes
  authorized outside of the folder picker due to view hierarchy
  inconsistencies. Fixes GH-44.
* Reset folder picker navigation title to nil when presenting the
  authorization webview.
* Ignore BoxSDKOAuth2ErrorAccessTokenExpired in error handler. This
  error code indicates the SDK is attempting an automatic refresh.
  It does not indicate a logged out state.
* Fix bug where navigation bar loses styling when the folder picker
  is dismissed and represented.
Fix XCode 5 and iOS 7 warnings

* Remove ARCH settings in xocdeproj for OS X builds
* Remove deprecated and unused trust result from BoxAuthorizationViewController

Fixes GH-63. Fixes GH-54.
Merge pull request #68 from box/xcode-5-ios7-warnings

Fix XCode 5 and iOS 7 warnings
Fix warnings from XCode analyzer

Fixes GH-71.
Merge pull request #72 from box/xcode-analyzer-warnings

Fix warnings from XCode analyzer
Kill ODRefreshControl and listen to notifications from the SDK only when appropriate in folder picker
Merge branch 'folder-picker-bugs'

Conflicts:
	BoxSDK.xcodeproj/project.pbxproj
Can no longer build with iOS 5.x SDK

{buildfix}
Update deployment target to 6.0
Prefix category methods on Foundation classes with 'box_'
Remove implementations of shouldAutorotateToInterfaceOrientation:

This method was deprecated in iOS 6. As of d4b4d410a5e7c96b230dec1bf8d355b32e4328a9,
the SDK targets iOS 6.0, dropping support for iOS 5.
Merge pull request #74 from box/category-prefix

Prefix category methods on Foundation classes with 'box_'
Merge pull request #75 from box/ios6-deprecation

Remove implementations of shouldAutorotateToInterfaceOrientation:
Updated copyright, license, and contribution guidelines
Merge branch 'master' into LightMail