Add integration tests for video verification

Enabling the "send password by Talk" property of shares require that
Talk is installed and enabled, so the Drone step that runs them has to
first clone the Talk repository.

When the integration tests are run on a local development instance,
however, it is not guaranteed that Talk is installed. Due to this the
"@Talk" tag was added, which ensures that any feature or scenario marked
with it will first check if Talk is installed and, if not, skip the
scenario (instead of failing).

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>