Fix parsing of dates when running specs in UTC

Travis runs specs in UTC.  This results in an unexpected hour component
in the finshed_at timestamp, causing that spec to fail.

Write the specs to be timezone-neutral at the cost of a little
clarity.
Fix spec for trend &darr; to work with Ruby 1.9.3

Ruby 1.9.3 can't parse the spec code because it contains a non-ascii
character (corresponding to &darr;).

Rewrite the code to look in the source (not the content) for the entity
(not the literal utf-8 character).
Add .travis.yml