Javascript-SDK - 3.0.0-alpha

This is the alpha release of the 3.0 SDK, which includes a number of improvements to audience targeting:

### New Features

- Support for number-valued and boolean-valued attributes ([#174](
- Support for audiences with new match conditions for attribute values, including 'substring' and 'exists' matches for strings; 'greater than', 'less than', 'exact, and 'exists' matches for numbers; and "exact" and 'exists' matches for booleans ([#174](

### Breaking Changes

- Previously, when a 'not' audience condition was applied to a malformed attribute, it was possible for the condition to evaluate to `true`. We’ve corrected this behavior, so that malformed attributes always evaluate to `null` and are ignored ([#174](