Use pathWithComponents: and stringByAppendingPathExtension: for better…

Use pathWithComponents: and stringByAppendingPathExtension: for better consistency with URL creation (+4 squashed commits)
Squashed commits:
[90e8970] Also use pathWithComponents: for "checkouts" with token and fixing tests by appending a slash to "api" and "meta"
[4eb36a4] No longer appending = for purposely blank values
[4c0f4e2] Improve method names, use of constants and appending .json when assembling the NSURLCompenents path at the end
[935cbb2] forgot to stage /meta

Improve method names, use of constants and appending .json when assembling the NSURLCompenents path at the end

No longer appending = for purposely blank values

Also use pathWithComponents: for "checkouts" with token and fixing tests by appending a slash to "api" and "meta"

Use pathWithComponents: and stringByAppendingPathExtension: for better consistency with URL creation

Mobile Buy SDK/Mobile Buy SDK/Utils/NSURLComponents+BUYAdditions.m

@@ -33,7 +33,8 @@
 	if (dictionary) {
 		NSMutableArray *queryItems = [NSMutableArray array];
 		for (NSString *key in [dictionary allKeys]) {
-			[queryItems addObject:[[NSURLQueryItem alloc] initWithName:key value:dictionary[key]]];
+			NSString *value = [dictionary[key] length] ? dictionary[key] : nil;
+			[queryItems addObject:[[NSURLQueryItem alloc] initWithName:key value:value]];
 		}
 		self.queryItems = [queryItems copy];
 	}