Get-Message doesn't work without any optional parameters

[absolutejam]

Would it make sense to have sensible defaults of $imap = @('SEEN','UNSEEN') if no other parameters are specified (I assume this will return all messages)?.

I can add a PR if that's a reasonable way to go about it.

The full exception:

PS C:\Users\administrator> $Session | Get-Mailbox 'Inbox' | Get-Message
Exception calling "Search" with "1" argument(s): "xm003 BAD Could not parse command"
At C:\Users\administrator\Documents\WindowsPowerShell\Modules\Gmail.ps\Gmail.ps.psm1:344 char:5
+     $result = $Session.Search('(' + $criteria + ')');
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : Exception