Added "make install" step to INSTALL.
Added "make install" step to INSTALL.

gdamjan/communi-desktop,communi/communi-desktop,communi/communi-symbian,jpnurmi/communi-desktop,communi/communi-symbian,communi/communi-symbian,sevanteri/communi-desktop,communi/communi-symbian,communi/communi-desktop