tests: increase opengcs tests verbosity
tests: increase opengcs tests verbosity

currently opengcs unit tests are not verbose enough and it's hard
to tell which tests are actually run. Increase verbosisty by
adding -v flag

Signed-off-by: Maksim An <b28a1069b720cf3786e288578c9a7f6f01d55828@microsoft.com>

Microsoft/hcsshim