Make Travis CI fetch Android NDK (see if it works ..)

.travis.yml

@@ -1,6 +1,17 @@
 language: java
 jdk:
   - oraclejdk8
+
 branches:
   only:
   - master
+
+before_install:
+  # required libs for android build tools
+  # sudo apt-get update
+  # sudo apt-get install -qq --force-yes libgd2-xpm ia32-libs ia32-libs-multiarch
+  # newest Android NDK
+  - wget http://dl.google.com/android/ndk/android-ndk-r10c-linux-x86_64.bin -O ndk.bin
+  - chmod +x ndk.bin
+  - ./ndk.bin
+  - export ANDROID_NDK_HOME=`pwd`/android-ndk-r10c