Fixed hard-to-find lua files and added Makefile targets

Hei, 

Jeg har jobbet litt med sosi2osm. Fint om du tar inn endringene (hvis du er fornøyd med dem)
i hovedgreina til sosi2osm.

Det er også .deb pakker tilgjengelig her https://launchpad.net/~saltmakrell/+archive/osm
og de kan installeres av Ubuntu 14.04 brukere med:
 sudo add-apt-repository ppa:saltmakrell/osm
 sudo apt-get update
 sudo apt-get install sosi2osm

Det vil også installere libfyba.

Mvh. Ruben

Commit message:

sosi2osm now looks for .lua files in /usr/local/share/sosi2osm/lua
and /usr/share/sosi2osm/lua if it cannot find the file in
./lua. This means that it is now possible to run sosi2osm from
wherever.

New Makefile target: install  - installs binary and lua files to
/usr/local/..

New Makefile target: uninstall  - removes all the files and folders
installed by install.

It looks for header files for libfyba also in /usr/include/..  now.