Merge pull request #59 from nmav/usage-fix

print usage when cannot open config file
Merge pull request #60 from nmav/simplify-startup

Simplify startup
Merge pull request #61 from nmav/fix-ssl3

Removed check which was refusing to check for extensions in SSL 3.0
Use pkg-config where available or detect the library using AC_LIB_HAVE_LINKFLAGS.

Signed-off-by: Nikos Mavrogiannopoulos <nmav@gnutls.org>