Fix issue #58: Add support for linking against GnuTLS for HTTPS support.

This commit adds support for building against the Debian/Ubuntu version
of GnuTLS using the OpenSSL wrappers.  See the README for details on how
to build with OpenSSL or GnuTLS and how to disable HTTPS completely in
Inadyn.  By default GnuTLS is now used.

Also bumps version to v1.99.10

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>