Use maintainer mode in configure

This will automatically rebuild Makefile and configure if needed,
preventing problems like the missing targets in
https://github.com/HoTT/HoTT/pull/286#issuecomment-30749614.  This means
that we now depend on having autobuild around to run ./configure and
make, though I think that systems without them will simply get warnings,
and not errors.
Merge pull request #290 from JasonGross/enable-maintainer-mode

Use maintainer mode in configure