Do not boot client if not in an environment that requires bugsnag

[atrauzzi]

If I'm in an environment that won't be making use of bugsnag, the library shouldn't require that a key even be provided. It should just fall through back to normal Laravel error reporting without attempting to instantiate the client.

[richstandbrook]

I agree, my continuous integration tests are failing because I'm not specifying an API key

[kattrali]

Thanks for the report @atrauzzi. This makes a lot of sense, and should be fixed soon in #86. Closing this however as a duplicate of #65.

[atrauzzi]

👍 :D