Correct the argument types of the StringBuilder.append

Modified AsmUtil to generate calls to more specific append methods in the StringBuilder class in order to save computation time and make less temporary objects.

Signed-off-by: Laszlo Hornyak <laszlo.hornyak@gmail.com>

results: http://dummywarhead.blogspot.ch/2014/05/hello-babel.html
bug: http://youtrack.jetbrains.com/issue/KT-5016