Bump CMake requirement to 2.8.5 in prep for GNUInstallDirs
Add comment so that java version check doesn't look redundant
Simplify/generalize code for finding library paths.

This is to accomodate multi-arch on Debian, as well as other situations
where the built-in computation of lib, lib32, or lib64 isn't what we want.
CMake-configurable headers now define libdir macros.
Start using GNUInstallDirs
Don't hardcode lib, share, include, bin in the CMake files.

This should complete "playing nicely in different distros" as well as multiarch.