Declare framework dependencies in podspec (#773)

Users may want to build the pod with Clang modules disabled -fno-modules because they are using ccache which doesn't support -fmodules. When modules are disabled, auto-linking of framework modules is also disabled, so these dependencies need to be expressed explicitly.

Analytics.podspec

@@ -17,7 +17,7 @@ Pod::Spec.new do |s|
   s.ios.deployment_target = '7.0'
   s.tvos.deployment_target = '9.0'
 
-  s.framework = 'Security'
+  s.frameworks = 'CoreTelephony', 'Security', 'StoreKit', 'SystemConfiguration', 'UIKit'
 
   s.source_files = [
     'Analytics/Classes/**/*',