Made colons quote-safe in logs; mainly for ipv6

Previous logging made a mess of ipv6 addresses. This just makes the
colon quote-safe so it passes through unscathed. The logs will still
be backward compatible because unquote don't care:

    $ python
    >>> from urllib import quote, unquote
    >>> quote('2001:db8:85a3:8d3:1319:8a2e:370:7348')
    '2001%3Adb8%3A85a3%3A8d3%3A1319%3A8a2e%3A370%3A7348'
    >>> unquote(quote('2001:db8:85a3:8d3:1319:8a2e:370:7348'))
    '2001:db8:85a3:8d3:1319:8a2e:370:7348'
    >>> quote('2001:db8:85a3:8d3:1319:8a2e:370:7348', '/:')
    '2001:db8:85a3:8d3:1319:8a2e:370:7348'
    >>> unquote(quote('2001:db8:85a3:8d3:1319:8a2e:370:7348', '/:'))
    '2001:db8:85a3:8d3:1319:8a2e:370:7348'

Change-Id: Ia13a9bc8a320cde5c56034a7f0b645913428bf21
Merge "Made colons quote-safe in logs; mainly for ipv6"