Fix iOS 9 warnings

- Require iOS 7 as base SDK  (for compiling)
- Hide deprecation message for NSURLConnection calls, these will be refactored soon
- Remove statusbar adjustment code (which isn't needed any longer)
- Remove kBITTextLabel... defines and use NSText.. instead
- Remove a few `#if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_6_1` since we require iOS 7 as base now (for real)

Classes/BITAuthenticationViewController.m

@@ -34,7 +34,6 @@
 #import "BITHockeyAppClient.h"
 
 @interface BITAuthenticationViewController ()<UITextFieldDelegate> {
-  UIStatusBarStyle _statusBarStyle;
   __weak UITextField *_emailField;
 }
 
@@ -66,24 +65,11 @@
 - (void)viewWillAppear:(BOOL)animated {
   [super viewWillAppear:animated];
   
-  _statusBarStyle = [[UIApplication sharedApplication] statusBarStyle];
-#if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_6_1
-  [[UIApplication sharedApplication] setStatusBarStyle:(self.navigationController.navigationBar.barStyle == UIBarStyleDefault) ? UIStatusBarStyleDefault : UIStatusBarStyleLightContent];
-#else
-  [[UIApplication sharedApplication] setStatusBarStyle:(self.navigationController.navigationBar.barStyle == UIBarStyleDefault) ? UIStatusBarStyleDefault : UIStatusBarStyleBlackOpaque];
-#endif
-  
   [self updateBarButtons];
   
   self.navigationItem.rightBarButtonItem.enabled = [self allRequiredFieldsEntered];
 }
 
-- (void)viewWillDisappear:(BOOL)animated {
-	[super viewWillDisappear:animated];
-  
-  [[UIApplication sharedApplication] setStatusBarStyle:_statusBarStyle];
-}
-
 #pragma mark - Property overrides
 
 - (void) updateBarButtons {
@@ -242,7 +228,7 @@
     textField.backgroundColor = [UIColor whiteColor];
     textField.autocorrectionType = UITextAutocorrectionTypeNo;
     textField.autocapitalizationType = UITextAutocapitalizationTypeNone;
-    textField.textAlignment = kBITTextLabelAlignmentLeft;
+    textField.textAlignment = NSTextAlignmentLeft;
     textField.delegate = self;
     textField.tag = indexPath.row;