Merge pull request #129 from mixpanel/jared-ios-version-315

bump mixpanel-swift to 3.1.5

Author: jaredmixpanel

MixpanelReactNative.podspec

@@ -19,5 +19,5 @@ Pod::Spec.new do |s|
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES' }  
 
   s.dependency "React"
-  s.dependency "Mixpanel-swift", '3.1.2'
+  s.dependency "Mixpanel-swift", '3.1.5'
 end