implement consoleLogs capability

The [WebDriver capabilities object](https://code.google.com/p/selenium/wiki/JsonWireProtocol#Capabilities_JSON_Object) is great, but it doesn't keep track of all implementations and their incompatibilities with the spec. This PR introduces the concept of inferred capabilities based on browser names and versions where we can specific what will and won't work.

This allows a consumer to check for the browser's ability to properly retrieve console logs before attempting to do so.