nsq_to_file: zero pad <REV>
nsqd: change --tls-required to a new tlsRequiredOption type

The new tlsRequiredOption takes "true", "false", and "tcp-https".
"true" and "false" (and variations allowed by ParseBool) allow backwards
compatibility.

The new "tcp-https" option allows users to require tls on only the
https/tcp ports, but to bypass tls on the http port.

Somebody could set up nsqd on a server, expose the tcp/https ports,
lockdown the http port, and allow localhost programs to post to nsqd
without adding support for certs/ssl.
Merge pull request #475 from twmb/no_tls_http_474

nsqd: extend --tls-required to allow non-tls on the http port
go fmt nsq_to_nsq
switch tlsRequiredOption.String to use strconv.FormatInt

This changes nothing output wise, but removes unnecessary code
and makes this method more generic for the future.
Add tls-min-version option

This adds a new tls-min-version flag that enables nsqd users
to specify a min tls version acceptable. The arguments to this
flag, <v>, follow the format of Version<v> in the tls package.

This commit adds --tls-min-version=ssl30 to the test.sh flags.
Merge pull request #513 from twmb/tls_min_version_512

nsqd: add --tls-min-version config option
travis: run tests on 1.3.3 and 1.4
switch to string for tls-min-version; default to 1.0 and max 1.2
Merge pull request #518 from jehiah/tls_min_max_518

TLS min/max version updates