Fixes crash after multiple setRoot

lib/ios/RNNCommandsHandler.m

 	[self assertReady];
 	
 	[_modalManager dismissAllModalsAnimated:NO];
+	[_store removeAllComponents];
 	
 	UIViewController *vc = [_controllerFactory createLayoutAndSaveToStore:layout[@"root"]];
 	

lib/ios/RNNStore.h

 
 @interface RNNStore : NSObject
 
--(UIViewController*) findComponentForId:(NSString*)componentId;
--(void) setComponent:(UIViewController*)viewController componentId:(NSString*)componentId;
--(void) removeComponent:(NSString*)componentId;
--(void) removeComponentByViewControllerInstance:(UIViewController*)componentInstance;
+- (UIViewController*)findComponentForId:(NSString*)componentId;
+- (void)setComponent:(UIViewController*)viewController componentId:(NSString*)componentId;
+- (void)removeComponent:(NSString*)componentId;
+- (void)removeComponentByViewControllerInstance:(UIViewController*)componentInstance;
+- (void)removeAllComponents;
 
 - (void)registerExternalComponent:(NSString *)name callback:(RNNExternalViewCreator)callback;
 - (UIViewController *)getExternalComponent:(NSString *)name props:(NSDictionary*)props bridge:(RCTBridge*)bridge;
 
--(NSString*)componentKeyForInstance:(UIViewController*)instance;
+- (NSString*)componentKeyForInstance:(UIViewController*)instance;
 
--(void) setReadyToReceiveCommands:(BOOL)isReady;
--(BOOL) isReadyToReceiveCommands;
+- (void)setReadyToReceiveCommands:(BOOL)isReady;
+- (BOOL)isReadyToReceiveCommands;
 
--(void) clean;
+- (void)clean;
 
 @end

lib/ios/RNNStore.m

 	}
 }
 
+- (void)removeAllComponents {
+	[_componentStore removeAllObjects];
+}
+
+
 -(void)setReadyToReceiveCommands:(BOOL)isReady {
 	_isReadyToReceiveCommands = isReady;
 }
 
 -(void)clean {
 	_isReadyToReceiveCommands = false;
-	[_componentStore removeAllObjects];
+	[self removeAllComponents];
 }
 
 -(NSString*)componentKeyForInstance:(UIViewController*)instance {