Revert "rollback ZAS"

This reverts commit 46eade7462cd6b4c6ac4cc3e42902b8f55cd028d.
Merge pull request #60 from zendesk/likun/zas_1.15.0

Revert "rollback ZAS"
bump 1.18.0 for CommonJS support
Merge branch 'master' into olaf/multiple_apps