update sdk version

With this commit I would like to trigger a new build on Travis.
I copied your Travis config (thanks for that) in my project but looks like there are problems with the emulator.  The error is:

```bash
$ ./wait_for_emulator
home/travis/build.sh: line 144: ./wait_for_emulator: Permission denied

The command "./wait_for_emulator" failed and exited with 126 during before_script.
```

Let's see if your project is still building :-)