Version bump

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/build.gradle

@@ -16,8 +16,8 @@ android {
         applicationId 'com.wireguard.android'
         minSdkVersion 21
         targetSdkVersion 27
-        versionCode 426
-        versionName '0.0.20180616'
+        versionCode 427
+        versionName '0.0.20180625'
     }
     // If the keystore file exists
     if (keystorePropertiesFile.exists()) {