Removed verbose default setting

This commit removes the default `verbose: true`.

After upgrading to paperclip-optmiser 1.0.0 (paperclip 3.5.2), my application's tests became way too verbose because of this default behavior:

![paperclip-optimiser-too-verbose](https://f.cloud.github.com/assets/132/1953534/d726f454-81c0-11e3-8aa3-c09010e13015.png)