update peerDependency

Simple PR, had to update the peerDependency, otherwise could not use with Hapi 3.0.

Tests say:

```bash
» npm test                  

> hapi-auth-basic@1.0.0 test /Users/david/Dropbox/Code/nodesecurity/hapi-auth-basic
> make test-cov



  ......................

 22 tests complete (104 ms)



 No global variable leaks detected.

Coverage: 100.00%
Coverage succeeded
```
All seems pretty fine :) Also closes this one https://github.com/spumko/hapi-auth-basic/issues/1