Remove warning about Makefile.am

We remove the configure script from the repository to avoid the
following error if the user does not have use the ./autogen.sh.
(Closes #6, #7 and #9).

Two modes to distribute RVLE.

- User uses the Git repository:

	cd rvle
	./autogen.sh
	cd ../
	R CMD INSTALL rvle

- User uses the released tarball:

	R CMD INSTALL rvle_1.0.1-2.tar.gz
Add default autotools files