build: disable documention on xapian for travis-ci. --disable-documentation passed to configure doesn't work and I have a crash in sphinx that prevents testing. Use -enable-documentation=no which appears to be how 1.4.14 expects it at least. no-github-ci to disable testing for github as this change affects travis only at this point. If it works, I'll disable doc build on github to to save cycles.

#!/usr/bin/env python

# Roundup requires Python 2.7+ as mentioned in doc\installation.txt
from __future__ import print_function
import sys

VERSION_NEEDED = (2, 7)

if sys.version_info < VERSION_NEEDED:
    print("Content-Type: text/plain\n")
    print("Roundup requires Python %s.%s or newer." % VERSION_NEEDED)
    sys.exit(0)