UnixTime: update output to include the epoch.

This is in service to some submarine commits which will be arriving soon
to deal with Goodies templating.  This makes UnixTime look "more like it
will" in addition to supplying what we determined to be the supplied
epoch.

This is most useful in the "empty" epoch case where we will tell them
the current epoch which may be of interest.
UnixTime: remove `time` trigger.

This eliminates the conflict with the preferred W|A answer.

Addresses #607.
UnixTime: update comment.
UnixTime: clean up eval a bit.

- Don't handle milliseconds with such a blunt trigger.  That's just
  plain silly.
- Replace `eval` with `try` from Try::Tiny.
UnixTime: switch to regex trigger.

This seemed like the easiest way to not trigger on an empty "epoch" or
"timestamp" but to work with all the other combos.
UnixTime: apply HTML table and styling.

An attempt to get a nicer look.
UnixTime: try yet another style.

HTML version unabashedly stolen from SubnetCalc.

Thanks to @mintsoft for the suggestion.
UnixTime: expand triggering.

- Allow for triggers at either end.
- Allow for negative epochs.
- Replace regex trigger with words trigger.
Merge pull request #608 from mwmiller/unix_time_changes

Unix Time Updates.