fix some imports so we don't depend on pch file

this is useful if this is being added to a dynamic framework

Classes/Explorer Toolbar/FLEXManager.h

@@ -7,6 +7,7 @@
 //
 
 #import <Foundation/Foundation.h>
+#import <UIKit/UIKit.h>
 
 @interface FLEXManager : NSObject
 

Classes/Global State Explorers/FLEXFileBrowserFileOperationController.m

@@ -7,6 +7,7 @@
 //
 
 #import "FLEXFileBrowserFileOperationController.h"
+#import <UIKit/UIKit.h>
 
 @interface FLEXFileBrowserFileDeleteOperationController () <UIAlertViewDelegate>
 

Classes/Network/FLEXNetworkTransaction.h

@@ -7,6 +7,7 @@
 //
 
 #import <Foundation/Foundation.h>
+#import "UIKit/UIKit.h"
 
 typedef NS_ENUM(NSInteger, FLEXNetworkTransactionState) {
     FLEXNetworkTransactionStateUnstarted,

Classes/Network/PonyDebugger/FLEXNetworkObserver.h

@@ -12,6 +12,8 @@
 //  which Square, Inc. licenses this file to you.
 //
 
+#import <Foundation/Foundation.h>
+
 extern NSString *const kFLEXNetworkObserverEnabledStateChangedNotification;
 
 /// This class swizzles NSURLConnection and NSURLSession delegate methods to observe events in the URL loading system.