Add basic autogen.sh

Since the buildsystem is now automake based, and a simple autoreconf
doesn't work, this adds a basic autogen.sh to automate building the
configure script.
Remove libtoolize from autogen

We don't need libtool support, so remove libtoolize from the autogen
script (and create build-aux to prevent errors when installing missing
components required by automake).

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>