build: Upgrade underlying NFD/ndn-cxx to 0.7.0

Change-Id: I3b0b3a6c5b64ce821ca5a0f7831220d01594fa70
diff --git a/app/build.gradle b/app/build.gradle
index 7de47dd..ed87e86 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -9,8 +9,8 @@
         applicationId "net.named_data.nfd"
         minSdkVersion 23
         targetSdkVersion 29
-        versionCode 4013
-        versionName "0.6.6-1 (NFD 0.6.6)"
+        versionCode 4018
+        versionName "0.7.0-1 (NFD 0.7.0)"
         multiDexEnabled true
     }
     compileOptions {