Restructuring namespace, config and TraceKit

This should have been at least a few commits -- my bad. Here's what it does:

- Namespaces TraceKit to Honeybadger.TraceKit using TraceKit.noConflict(), which means the vendored tracekit.js is now self-contained within honeybadger.js.
- Extracts configuration to its own class
- Converts the Honeybadger namespace to a vanilla Object rather than a class.
Delete old todos
Add Honeybadger.wrap() function for #17