fix testnet (#227)

* fix testnet

* -move buildConfigFiled inside flavour
-rename SERVER_URL to DEFAULT_SERVER_URL

app/build.gradle

@@ -38,11 +38,13 @@ android {
         zcashtestnet {
             dimension 'network'
             applicationId 'cash.z.ecc.android.testnet'
+            buildConfigField "String", "DEFAULT_SERVER_URL", '"lightwalletd.testnet.electriccoin.co"'
             matchingFallbacks = ['zcashtestnet', 'debug']
         }
 
         zcashmainnet {
             dimension 'network'
+            buildConfigField "String", "DEFAULT_SERVER_URL", '"lightwalletd.electriccoin.co"'
             matchingFallbacks = ['zcashmainnet', 'release']
         }
     }

app/src/main/java/cash/z/ecc/android/ext/Const.kt

@@ -1,5 +1,7 @@
 package cash.z.ecc.android.ext
 
+import cash.z.ecc.android.BuildConfig
+
 object Const {
     /**
      * Named objects for Dependency Injection.
@@ -42,7 +44,7 @@ object Const {
     object Default {
         object Server {
             // If you've forked the ECC repo, change this to your hosted lightwalletd instance
-            const val HOST = "lightwalletd.electriccoin.co"//"your.hosted.lightwalletd.org"
+            const val HOST = BuildConfig.DEFAULT_SERVER_URL
             const val PORT = 9067
         }
     }