generic: support building on OS X, refs #74

CMakeLists.txt
	- etl is built as a .app bundle on OS X

easybuild.sh
	- OS X by default does not bundle curl (no point)
	- Because the client is built as a .app on OS X, the install directories are tweaked a bit

misc/Info.plist
	- Updated to use the vars specified in CMakeLists.txt

src/sys_main.m
	- Changes to handle dylibs instead of only just the old-school zipped .bundle packages on OS X
	- main() was tweaked to set Sys_BinaryPath to the parent of the .app on OS X