FreeImage manitenance

[Zachary Pincus]

Hi all,

Apropos of the recent discussion about and troubles with diagnosing FreeImage library loading problems on 64-bit windows, I have tried to enhance the library-loading code:
https://github.com/scikits-image/scikits-image/pull/117

And speaking of FreeImage and 64-bit-ness, 
https://github.com/scikits-image/scikits-image/pull/112
fixes some problems in 64-bit image loading, and also clarifies how to deal with 64-bit pointers and the ctypes interface.

Finally, 
https://github.com/scikits-image/scikits-image/pull/113
builds on the changes in PR 112 to expose basic image metadata reading in a 64-bit-safe manner. 

Comments welcome.

Zach