Revert "Configure URLSession to wait for connectivity"

This reverts commit 7a34318.

NSURLSession's waitsForConnectivity also applies to unavailable hosts
even when internet connectivity is available. This is undesirable for
Vienna, since it means that those connections clog up the connections
queue or block it completely if the maximum number of connections is
reached (10 by default).

Author: Eitot

Vienna/Sources/Fetching/RefreshManager.m

@@ -96,7 +96,6 @@ -(instancetype)init
         config.HTTPAdditionalHeaders = @{@"User-Agent": userAgent()};
         config.HTTPMaximumConnectionsPerHost = 6;
         config.HTTPShouldUsePipelining = YES;
-        config.waitsForConnectivity = YES;
         _urlSession = [NSURLSession sessionWithConfiguration:config delegate:self delegateQueue:[NSOperationQueue mainQueue]];
 
         NSNotificationCenter * nc = [NSNotificationCenter defaultCenter];