Mainly small install script improvements - Consistent usage of `$LUANHOME`, removed reliance on current directory. - Made Luan build and install fine (on Linux) without requiring launching it via sudo. Only asks to elevate privileges if installation failed. - Minor spelling mistake fix.

LUAN_HOME=`pwd`

CLASSPATH=$LUAN_HOME/src
CLASSPATH=$CLASSPATH:$LUAN_HOME/slf4j/src

for file in $LUAN_HOME/lib/*; do
	CLASSPATH=$CLASSPATH:$file;
done

export CLASSPATH