Ignoring more rule types when parsing, updating api, and updates to package.json

* Ignoring `keyframes`, `font-faces`, and `imports` when parsing. These will not impact the selector limit. Although test coverage for `keyframes` have been added, the feature is not supported below IE10.
* `require('parser')` does not make sense for modules that consume `bless.js`. Renaming `parser` back to `bless`, with `parser` being exported in an object.
* `npm` does not support a `build` script, but it does support `prepublish` which executes a build script after `npm install`