TableRow class added

Created a class for rows in a step's table.
Spec update

Added some additional specs for Table objects that should have been
there from the start.
Spec update

Swapped out #== for #equal? in several of the specs in order to better
capture the intent of the test.
History update

Updating gem history in preparation for v1.4.0 release.
Version bump

Gem version bumped for v1.4.0 release.