[ios] Converted iOS SDK into dynamic framework

make iproj now produces a target that pulls together static libraries like core and platform-ios into a real dynamic framework. iosapp is pretty much just a regular iOS application that links Mapbox.framework (except for the inclusion of default_styles.hpp). iosapp runs fine in the Simulator and on a device, and the same is true for any application linking against Mapbox.framework.

The ipackage target produces both a Bitcode-disabled static framework and a Bitcode-enabled dynamic framework, eliminating the need for a separate framework.sh. It disables code signing, since that happens on copy when the framework is embedded inside the application bundle. It also merges the device and simulator builds into a single fat framework.

Also bumped itest minimum deployment target to iOS 8.0, the first version that supports linking frameworks.

Fixes #828.

ios/Mapbox-iOS-SDK.podspec

@@ -22,16 +22,7 @@ Pod::Spec.new do |m|
 
   m.requires_arc = true
 
-  m.preserve_paths = '**'
-  m.resource_bundle = { 'Mapbox' => 'Mapbox.framework/Mapbox.bundle/*' }
-  m.vendored_frameworks = 'Mapbox.framework'
+  m.vendored_frameworks = 'dynamic/Mapbox.framework'
   m.module_name = 'Mapbox'
 
-  m.frameworks = 'CoreLocation', 'GLKit', 'ImageIO', 'MobileCoreServices', 'QuartzCore', 'SystemConfiguration'
-  m.libraries = 'c++', 'sqlite3', 'z'
-  m.pod_target_xcconfig = {
-    'OTHER_CPLUSPLUSFLAGS' => '-std=gnu++11 -stdlib=libc++',
-    'OTHER_LDFLAGS' => '-ObjC',
-  }
-
 end