Move configuring Braintree logger to `set_configuration`
Move configuring Braintree logger to `set_configuration`

This ensures that nothing is configured at the time this library loads,
but only when `activate!` gets called.

It also keeps all Braintree configuration at the same place.

twalpole/fake_braintree,github/fake_braintree,highfidelity/fake_braintree,twalpole/fake_braintree,wacii/fake_braintree,foraker/fake_braintree,foraker/fake_braintree,wacii/fake_braintree,highfidelity/fake_braintree,rochers/fake_braintree,rochers/fake_braintree