Need to detect cross-device renameing

[Hypercubed]

I was struggling with this last night. Apparently you cannot fs.rename across devices.

• http://stackoverflow.com/questions/4568689/how-do-i-move-file-a-to-a-different-partition-in-node-js
• https://github.com/joyent/node/issues/936

Maybe do this?

• https://github.com/SeyZ/mongoose-attachments-localfs/commit/a2f9b7e0289cb546e06ecb33ea8f1ccaea542fba

[satazor]

Good catch, I've reviewed #2. I will be merging after you update it!

[satazor]

2 does not work on Windows. Need to find a better solution, perhaps copy and delete.