Remove useless codes
Re-implement SRWindowManager:

Swift sucks to use Carbon or some C APIs.
So I re-implemented some class with Objective-C language.

There's a new class named SRWindow. This class is very specialized class
for present window informations and any operations. (for future!)
Refactoring
Implement property SRWindowManager.applicationWindows
Merge pull request #13 from seorenn/devel

Updates for SRWindowManager