makefile: Add "install" case
makefile: Add "install" case

In order to install the kata-proxy binary from the Makefile, this
commit adds a new entry "install" to it.

Fixes #23

Signed-off-by: Sebastien Boeuf <90b401417360b1924ef3f520ddee932686110f85@intel.com>

amshinde/shim,amshinde/shim