Added pickled pic object loading for performance boost
Added support for pickled Pic objects

* Saving and loading pickled Pic objects is much faster than getting
information about every picture every time
* Added ability to download image at original resolution
* Added __str___, __repr___, and __cmp___ methods
Added ability to download original image

* Original image can be downloaded now. If the image is a JPEG, it is
send directly. If image is not JPEG, then it is converted at the same
resolution as the original.
* Direct exceptions to the error log. I feel this is more secure than
telling the user about the exception.