Merge pull request #138 from marcbonnici/apk_install

Ports `install_apk` and `get_sdk_version` from WA2
tree: 67428b0fd477112a2d43a5452c89323e6c41ba05
  1. devlib/
  2. doc/
  3. src/
  4. .gitignore
  5. README.rst
  6. setup.py