Use brew installed libraries instead of manually installed ones

[scj643]

I've been working with the source code and having to manully link all the libraries and their include directories get's annoying. I think that for libgphoto2 we should use the brew install paths to keep everything in a common path.

[scj643]

@bangnoise How do you have your libraries set up for the libgphot2 branch? I'm having issues with my newer builds.