shell_i: Use an NSConnection instead of a local socket owncloud#2340

This prepares the switch to the official FinderSync API on Yosemite
which requires the extension to run in a sandbox. This complicates
the usage of a local socket to communicate with a non-sandboxed GUI
client. An NSConnection is easier to use in this case, which we can
use as long as the server name (i.e. Mach port registered name) is
prefixed with the code signing Team Identifier.

A placeholder server implementation is also added to the client's
SocketApi which basically reproduces the interface of a QLocalSocket.
Most of the references to individual sockets we're only using
QIODevice methods so the type was simply reduced. A typedef to
replace the QLocalServer was the only other part needed.

shell_integration/MacOSX/OwnCloudFinder/ContentManager.m

@@ -149,11 +149,11 @@ - (NSNumber*)iconByPath:(NSString*)path isDirectory:(BOOL)isDir
 	// NSLog(@"XXXXXXX Asking for icon for path %@ = %d",normalizedPath, [result intValue]);
 
 	if( result == nil ) {
-		// start the async call
-		[[RequestManager sharedInstance] askForIcon:normalizedPath isDirectory:isDir];
 		result = [NSNumber numberWithInt:0];
 		// Set 0 into the cache, meaning "don't have an icon, but already requested it"
 		[_fileNamesCache setObject:result forKey:normalizedPath];
+		// start the async call
+		[[RequestManager sharedInstance] askForIcon:normalizedPath isDirectory:isDir];
 	}
 	if ([result intValue] == 0) {
 		// Show the old state while we wait for the new one