The available version of cmake for Ubuntu 12.04 is too old.
The PPA listed does not currently work so the official
cmake webisite is a more reliable source to get cmake.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Enable build of posix_eagle_release.
Added path to ARM cross compiler in qrlsdk install.
Fixed warnings in Toolchain-arm-linux-gnueabihf.cmake

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

-move uavcan submodule to src/modules/uavcan/libuavcan
-adding libuavcan as a subdirectory simplifies inheriting all compile
flags and include paths