Bump NPM version to 0.9.0 in preparation for publishing.
Bump NPM version to 0.9.0 in preparation for publishing.

The minor version bump is due to the significant code changes involved in
https://github.com/benjamn/ast-types/pull/145, even though no behavioral
changes are expected.

benjamn/ast-types,benjamn/ast-types,benjamn/ast-types