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.

#! /bin/sh

# if there are multiple trackers, d=demo t=tracker ...
# returns last one for testing that server is up. Does not test
# each tracker.
tracker=$(ps -ef | sed -ne '/roundup-server/s/^.*\s\(\w*\)=.*$/\1/p')
wget -q -O /dev/null --no-verbose http://localhost:8080/${tracker:-demo}/