Rework template logic

ANSI escapes are now constants, so they are more readable
Re-instate the ERb logic that was previously lost
Undo travis_print_color_coded_result

ERb processing may leave us with `echo ' >> …'`, which is not what we
want.

Instead, undo the travis_print_color_coded_result function, rather
than messing with the bash function.  Duplication seems acceptable,
since it happens only twice.
Add highlight to travis_wait output
Merge pull request #221 from travis-ci/ha-feature-highlight-nonzeo-exit-status

Rework template logic