Update Whoops version to 1.0.6

This PR updates the Whoops version used in Laravel to 1.0.6. The changes are mostly bug-fixes and small feature implementations, with no known BC-breaks.

Some interesting additions to the API are an overhauled `FrameCollection` (easier to, for example, filter frames from a stack trace), serializable `FrameCollection` and `Frame` objects, lazy data tables, and support for clickable URIs in frame comments within `PrettyPageHandler`.

More tests were also added for both new and old features.

Full compare view from `1.0.1` to `1.0.6`:
https://github.com/filp/whoops/compare/1.0.1...1.0.6

Cheers!