fix incompatibility with Twisted 13.1.0

The fix is to stop using a locally-defined "getPage" which does better
clean-up-after-itself with the standard twisted.web.client.getPage instead. (By
the way, I disapprove of cleaning-up-after-oneself. Instead, whenever one is
done with one's job, the entire universe in which one lives gets destroyed.)
git-foolscap: minor typo
remove dead code, thanks zooko for the catch. Closes #211.
test_logging: tolerate DOS path-separators. Closes #204.
flappserver: explicitly reject unicode in stdin. For #209.
accept new-style connection hints

Accept TCP connection hints in the new Twisted Endpoints syntax (e.g.
"tcp:host=127.0.0.1:port=9999").

Also, be more picky about what we take to be an old-style host:port connection
hint (for example, accept only a certain class of characters in hostnames, and
accept only port numbers that are 1 to 5 digits long).

If a connection hint is neither a new-style TCP Endpoint string, nor matches
the (now tighter) old-style host:port string, then it will be ignored. (This
makes it easy for future versions of foolscap to put other forms of connection
hints into furls, knowing that foolscap 0.7 will ignore them.)

Also, we no longer require ignored connection hints to contain a ':'.
referenceable.py: update comments a bit
ChangeLog: stop updating, rename to ChangeLog.0.6.4

This makes it clear that the ChangeLog is no longer updated with each
commit. Please refer to git logs for this level of detail.
remove spurious trailing spaces
enable travis testing
promise.py: make compatible with Twisted-14.0.0

twisted.python.util.unsignedID was removed in Twisted-14.0.0 . We used
it to handle very old pythons (py2.4/py2.5) in which id() sometimes
returned a negative number. This only affects the cosmetic repr() of a
Promise, so this probably doesn't affect 2.4/2.5 compatibility (which is
currently untested).
promise.py: remove unused import, appease pyflakes
travis: also run pyflakes
travis: install pyflakes
temp pr12 stuff