Linux/OSX support

[JeroMiya]

In a few places, OSVR-Config does not work out of the box on Linux:

• There is no launcher script or application (the OSVR-Config.exe is a windows .Net application, though I could port this to CoreCLR.
• There is no build script for Linux [Fixed].
• When the launcher and the tools controllers launch executables, they currently hard-code the ".exe" extension. This needs to work on Linux where there will be no extension [Edit: Fixed in https://github.com/Added utility to get the cross-platform name of executables. #42].

[JeroMiya]

There is now a build script for Linux, and project is updated to work on at least Ubuntu. Other issues remain, and should add the Mac OS X runtime to the runtimes list or figure out how to get a standalone build without an explicit runtime list.