use minify for release with proper proguard rules (#175)

Author: thomaszurkan-optimizely

test-app/build.gradle

@@ -16,7 +16,7 @@ android {
     }
     buildTypes {
         release {
-            minifyEnabled false
+            minifyEnabled true
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }

test-app/proguard-rules.pro

@@ -27,6 +27,9 @@
 
 # Safely ignore warnings about other libraries since we are using Gson
 #-dontwarn com.fasterxml.jackson.**
+-keep class com.fasterxml.jackson.** {*;}
+-dontwarn com.google.gson.**
+-dontwarn com.optimizely.ab.config.parser.**
 #-dontwarn org.json.**
 
 # Annotations
@@ -37,6 +40,7 @@
 
 # slf4j
 #-dontwarn org.slf4j.**
+-keep class org.slf4j.** {*;}
 
 # Android Logger
 #-keep class com.noveogroup.android.log.** { *; }