Fixed automake 1.14 bug

automake 1.14 would fail with global options already processed, due to AM_INIT_AUTOMAKE being called twice (top of configure.ac and in FB_INITIALIZE)

Fixes installations issues on systems with automake 1.14, such as [FreeBSD 9.1](http://forums.freebsd.org/showthread.php?t=40903) or OS X (#51)