Fix issue #291 TAP output type is broken in 2.0rc3

The success and failure format strings were bypassed in commit 88f7850.

Now, if the following two tests are run with TAP output, we will get the
expected ok/not ok formats.

$ bin/busted -o TAP spec/cl_spec.lua
1..1
ok 1 - Tests the busted command-line options

$ bin/busted -o TAP spec/cl_two_failures.lua
1..2
not ok 1 - Runs 2 failing tests is failing test 2
(details omitted)
not ok 2 - Runs 2 failing tests is failing test 1
(details omitted)