iOS app/framework fixes for v8

- Mapbox Streets -> Streets
 - style version from string to integer
 - 7 -> 8

ios/app/MBXViewController.mm

@@ -9,7 +9,7 @@
 static UIColor *const kTintColor = [UIColor colorWithRed:0.120 green:0.550 blue:0.670 alpha:1.000];
 
 static NSArray *const kStyleNames = @[
-    @"Mapbox Streets",
+    @"Streets",
     @"Emerald",
     @"Light",
     @"Dark",
@@ -19,7 +19,7 @@ static NSArray *const kStyleNames = @[
     @"Satellite",
 ];
 
-static NSString *const kStyleVersion = @"7";
+static NSUInteger const kStyleVersion = 8;
 
 @interface MBXViewController () <UIActionSheetDelegate, MGLMapViewDelegate>
 
@@ -301,9 +301,9 @@ mbgl::Settings_NSUserDefaults *settings = nullptr;
     }
 
     self.mapView.styleURL = [NSURL URLWithString:
-        [NSString stringWithFormat:@"asset://styles/%@-v%@.json",
-            [[styleName lowercaseString] stringByReplacingOccurrencesOfString:@" " withString:@"-"],
-            kStyleVersion]];
+        [NSString stringWithFormat:@"asset://styles/%@-v%lu.json",
+            [styleName lowercaseString],
+            (unsigned long)kStyleVersion]];
 
     [titleButton setTitle:styleName forState:UIControlStateNormal];
 }

platform/ios/MGLMapView.mm

@@ -39,11 +39,12 @@
 
 class MBGLView;
 
-NSString *const MGLDefaultStyleName = @"mapbox-streets";
-NSString *const MGLStyleVersion = @"7";
+NSString *const MGLDefaultStyleName = @"streets";
 NSString *const MGLDefaultStyleMarkerSymbolName = @"default_marker";
 NSString *const MGLMapboxSetupDocumentationURLDisplayString = @"mapbox.com/guides/first-steps-gl-ios";
 
+NSUInteger const MGLStyleVersion = 8;
+
 const NSTimeInterval MGLAnimationDuration = 0.3;
 const CGSize MGLAnnotationUpdateViewportOutset = {150, 150};
 const CGFloat MGLMinimumZoom = 3;
@@ -190,9 +191,9 @@ std::chrono::steady_clock::duration secondsAsDuration(float duration)
 
     if ( ! styleURL)
     {
-        styleURL = MGLURLForBundledStyleNamed([NSString stringWithFormat:@"%@-v%@",
+        styleURL = MGLURLForBundledStyleNamed([NSString stringWithFormat:@"%@-v%lu",
                                                MGLDefaultStyleName.lowercaseString,
-                                               MGLStyleVersion]);
+                                               (unsigned long)MGLStyleVersion]);
     }
 
     if ( ! [styleURL scheme])