Implemented better support for Dash. Closes tomaz#217.

Dash can take advantage of appledoc generated documentation sets by displaying TOC and click to copy. To be able to do so, it requires `--docset--platform-family` value to be `appledoc`. Current documentation set reference doesn't mention this key anymore, so it seems safe to hijack it. If this isn't desired, you can still revert to empty string or whichever value you want by explicitly using the cmd line switch (of course, you can also do it inside project or global settings plist files).

Application/GBApplicationSettingsProvider.m

@@ -123,7 +123,7 @@ - (id)init {
 		self.docsetFeedURL = @"";
 		self.docsetPackageURL = @"";
 		self.docsetMinimumXcodeVersion = @"3.0";
-		self.docsetPlatformFamily = @"";
+		self.docsetPlatformFamily = @"appledoc"; // this makes docset TOC usable from within Dash - http://kapeli.com/dash/
 		self.docsetPublisherIdentifier = [NSString stringWithFormat:@"%@.documentation", kGBTemplatePlaceholderCompanyID];
 		self.docsetPublisherName = [NSString stringWithFormat:@"%@", kGBTemplatePlaceholderCompany];
 		self.docsetCopyrightMessage = [NSString stringWithFormat:@"Copyright © %@ %@. All rights reserved.", kGBTemplatePlaceholderYear, kGBTemplatePlaceholderCompany];