Fixed 'make install' generating wrong dropbox wrapper script (#3)

`make install` created the dropbox wrapper script with the wrong first
line: -e #!/bin/bash

This patch replaced the echo in the Makefile with a copy of an external
file. The new dropbox file uses `dirname` to be path-agnostic.

Author: Uplink03

Makefile

@@ -11,8 +11,7 @@ clean:
 
 install: libdropbox_ext4.so
 	install $^ $(INSTALL_DIR)/lib/ && \
-	echo -e "#!/bin/bash\n\nLD_PRELOAD=$(INSTALL_DIR)/lib/$^ exec /usr/bin/dropbox \"\$$@\"" > $(INSTALL_DIR)/bin/dropbox && \
-	chmod 0755 $(INSTALL_DIR)/bin/dropbox
+	install dropbox $(INSTALL_DIR)/bin/dropbox
 
 uninstall:
 	rm -f $(INSTALL_DIR)/bin/dropbox && \

dropbox

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+Dir=$(dirname "$0")
+
+LD_PRELOAD="$Dir"/../lib/libdropbox_ext4.so exec /usr/bin/dropbox "$@"