Fixes to work with BinDeps/Homebrew properly

Use the auto-generated `deps/deps.jl` file which caches binary object locations.  This is what gets created from `Pkg.build()`.  Use those cached locations in your `ccall`'s, as we don't mess around with global linker search paths that much anymore, since caching the full path is a lot faster.

Note that since you're creating a little shim this won't work on OSX machines that don't have a compiler.  If you'd like to distribute binaries of your shim, (best-case scenario, write that in Julia as well, with the upcoming multithreading capabilities, if that turns out to be possible) I may be able to help you with that.