adding ClientOptions::withoutMessageLogging

[Brett McBride (brettmc)]

As a follow-up patch to #294 this patch exposes the ability to disable the logging
of messages via ClientOptions. The default behaviour remains to continue to log messages.
Bumped the minimum required version of contentful/core to ^3.1 in anticipation that the next release will indeed be v3.1.
In passing, update the php-vcr version requirement to the latest version, as the branch it was trying to use no longer exists.

[Brett McBride (brettmc)]

Hello, here is my follow-up patch for disabling message logging (see #294).
I anticipated that the next release you'd do of contentful-core.php would be v3.1, so I've set the composer dependency to match.

[Paul Grigoruta (pgrigoruta)]

Thank you for your contribution Brett McBride (@brettmc) !

[Brett McBride (brettmc)]

Hi Paul Grigoruta (@pgrigoruta) - contentful/core lib definitely does have new changes that this patch relies on, namely contentful/contentful-core.php#43. The patch won't work without those changes (I think it will silently do nothing) which is why I bumped the dependency up.
As a minimum, this change would require a new released version of contentful/core (composer may pick up the correct version anyway, but bumping the dependency to make it explicit felt like the "right way", according to semantic versioning).