[Nexus 7 (2013) LTE Android Development] Synman:
ok, that was a fun exercise... I brought AndroidAsync, ion, gson, and VoicePlus into my build environment and after a couple additional tweaks and proguard hints I got a good apk.... guess I should drop this puppy in /system/app and see what happens.

Proguard: out/target/common/obj/APPS/VoicePlus_intermediates/proguard.classes.jar
ProGuard, version 4.4
Reading program jar [/Volumes/android-4.4_r1.1/out/target/common/obj/APPS/VoicePlus_intermediates/classes.jar]
Reading library jar [/Volumes/android-4.4_r1.1/out/target/common/obj/JAVA_LIBRARIES/core_intermediates/classes.jar]
Reading library jar [/Volumes/android-4.4_r1.1/out/target/common/obj/JAVA_LIBRARIES/core-junit_intermediates/classes.jar]
Reading library jar [/Volumes/android-4.4_r1.1/out/target/common/obj/JAVA_LIBRARIES/ext_intermediates/classes.jar]
Reading library jar [/Volumes/android-4.4_r1.1/out/target/common/obj/JAVA_LIBRARIES/framework_intermediates/classes.jar]
Reading library jar [/Volumes/android-4.4_r1.1/out/target/common/obj/JAVA_LIBRARIES/framework2_intermediates/classes.jar]
Note: duplicate definition of library class [com.android.internal.telephony.ISms$Stub$Proxy]
Note: duplicate definition of library class [com.android.internal.telephony.ISms$Stub]
Note: duplicate definition of library class [com.android.internal.telephony.ISms]
Reading library jar [/Volumes/android-4.4_r1.1/out/target/common/obj/JAVA_LIBRARIES/telephony-common_intermediates/classes.jar]
Note: there were 3 duplicate class definitions.
Note: org.cyanogenmod.voiceplus.VoicePlusService accesses a method 'getService(java.lang.String)' dynamically
Maybe this is library method 'android.os.IServiceManager { android.os.IBinder getService(java.lang.String); }'
Maybe this is library method 'android.os.ServiceManager { android.os.IBinder getService(java.lang.String); }'
Maybe this is library method 'android.os.ServiceManagerProxy { android.os.IBinder getService(java.lang.String); }'
Maybe this is library method 'java.security.Provider { java.security.Provider$Service getService(java.lang.String); }'
Maybe this is library method 'org.apache.harmony.security.fortress.Services { java.security.Provider$Service getService(java.lang.String); }'
Note: com.koushikdutta.async.dns.Dns accesses a method 'join(java.net.InetAddress)' dynamically
Maybe this is library method 'java.net.DatagramSocketImpl { void join(java.net.InetAddress); }'
Maybe this is library method 'java.net.PlainDatagramSocketImpl { void join(java.net.InetAddress); }'
Note: com.google.gson.internal.UnsafeAllocator accesses a declared field 'theUnsafe' dynamically
Note: com.google.gson.internal.UnsafeAllocator accesses a method 'allocateInstance(java.lang.Class)' dynamically
Maybe this is library method 'sun.misc.Unsafe { java.lang.Object allocateInstance(java.lang.Class); }'
Note: there were 4 accesses to class members by means of introspection.
You should consider explicitly keeping the mentioned class members
(using '-keep' or '-keepclassmembers').
Preparing output jar [/Volumes/android-4.4_r1.1/out/target/common/obj/APPS/VoicePlus_intermediates/proguard.classes.jar]
Copying resources from program jar [/Volumes/android-4.4_r1.1/out/target/common/obj/APPS/VoicePlus_intermediates/classes.jar]
target Dex: VoicePlus
Copying: out/target/common/obj/APPS/VoicePlus_intermediates/classes.dex
target Package: VoicePlus (out/target/product/tilapia/obj/APPS/VoicePlus_intermediates/package.apk)
Warning: AndroidManifest.xml already defines versionCode (in http://schemas.android.com/apk/res/android); using existing value in manifest.
Warning: AndroidManifest.xml already defines versionName (in http://schemas.android.com/apk/res/android); using existing value in manifest.
Warning: AndroidManifest.xml already defines minSdkVersion (in http://schemas.android.com/apk/res/android); using existing value in manifest.
Warning: AndroidManifest.xml already defines targetSdkVersion (in http://schemas.android.com/apk/res/android); using existing value in manifest.
Install: out/target/product/tilapia/system/app/VoicePlus.apk