First cut at support for a 'make install'

[dkfellows]

The core of the fix for SpiNNakerManchester/SupportScripts#21

[rowleya]

Running make install currently fails in Ubuntu (on Windows) with:

Makefile:28: recipe for target 'install' failed
make: *** [install] Error 1

It isn't clear what went wrong, but Ubuntu doesn't like it...

Note that I didn't change my $SPINN_DIRS, so it currently points at the same place as the files come from, but this was the case I was trying to test (since this is how most users will have their systems configured currently; I wanted to see what would happen).

[rowleya]

Quick additional check; if I set $SPINN_DIRS before make, make fails:

make[1]: Entering directory '/mnt/c/Users/zzalsar4/git/spinnaker_tools/sark'
make[1]: *** No rule to make target '/home/zzalsar4/test_dir//include/spinnaker.h', needed by '../build/gnu/spinnaker.gas'.  Stop.
make[1]: Leaving directory '/mnt/c/Users/zzalsar4/git/spinnaker_tools/sark'
Makefile:22: recipe for target 'all' failed
make: *** [all] Error 2

If I do the same having already called make, I get the same error as above.

[Christian-B]

Is this PR worth keeping?