v0.6.1a: updated gradle stuff

SPD-classes/build.gradle

@@ -1,8 +1,8 @@
 apply plugin: 'com.android.library'
 
 android {
-    compileSdkVersion 25
-    buildToolsVersion "25.0.3"
+    compileSdkVersion 26
+    buildToolsVersion "26.0.1"
 
     task ndkBuild(type: Exec){
         description "builds JNI libs from source. " +

build.gradle

@@ -10,5 +10,6 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        google()
     }
 }

core/build.gradle

@@ -1,8 +1,8 @@
 apply plugin: 'com.android.application'
 
 android {
-    compileSdkVersion 25
-    buildToolsVersion "25.0.3"
+    compileSdkVersion 26
+    buildToolsVersion "26.0.1"
 
     buildTypes {
         debug {
@@ -12,7 +12,7 @@ android {
         release {
             shrinkResources true
             minifyEnabled true
-            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
         }
     }
 }

gradle/wrapper/gradle-wrapper.properties

@@ -2,4 +2,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip