Merge branch 'jk/tap-verbose-fix' into maint

Merge branch 'jk/tap-verbose-fix' into maint

The Travis CI configuration we ship ran the tests with --verbose
option but this risks non-TAP output that happens to be "ok" to be
misinterpreted as TAP signalling a test that passed.  This resulted
in unnecessary failure.  This has been corrected by introducing a
new mode to run our tests in the test harness to send the verbose
output separately to the log file.

* jk/tap-verbose-fix:
  test-lib: bail out when "-v" used under "prove"
  travis: use --verbose-log test option
  test-lib: add --verbose-log option
  test-lib: handle TEST_OUTPUT_DIRECTORY with spaces