Set version 1.1.7-SNAPSHOT in AndroidManifest and example pom's

Some example pom's already had the version 1.1.7-SNAPSHOT.
Add the --all flag to be able to download the android-8 platform
Update the android-sdk used on Travis

The android-sdk r21.1 does not recognize android-8 anymore, not even
with the --all flag. When using the latest version, r22.6.2, then the
update sdk command needs to explicitly specify build-tools (with a
specific version), and answer y to a question about license.