Improve Linux make system, pull in OculusSDK from jherico/OculusSDK as a git submodule rather than tracking it ourselves

With this, it pulls the latest 0.4.3 SDK from jherico's github and uses that instead. Additionally, it compiles all modules with '-O2' and some advantageous linker flags. It's still got the same segfault I was having before (and if someone could test if that happens on Windows without a rift that'd be grand) but this should make setting it up for dev much easier.

Please note that before running 'make' you must run 'git submodule init' 'git submodule update' and then in JRiftLibrary/OculusSDK run 'cmake .'