Improvements and refactoring into the QRCode and Email Module.

Renaming EmailSenderException to OMRGraderEmailException.
Improving the via for getting the information from the QR Code and creating the Key-pairs for the Student.java class.
Renaming SheetFileInfo to SheetFileInformation.
Renaming AnswerStudent to ExamResult.
Annotating the ExamSessionComparator as a Spring Component.
Creating File Filtering for images exams files.

Improvement the File Filter for images exams files into the ImageFileManager class.
Deleting unused values or constants in the WebServices Module.
Improving the management for the Request attribute in the GraderSession entity.
Getting performance in the OpenCV Process module.

Improving the attributes for the Exam DTO model.
Annotating the OMRGraderProcess and OpenCVLibraryLoader as Spring Beans.
Annotating the dependences between OMRGraderProcess and the OpenCVLibraryLoader beans.
Adding new packages to scanning for Spring Beans.
General improvements unrelated.

Deleting ununsed references for Spring Beans in the GraderSessionDispatcherThread.
Improving the source code writing for the utility class: UIText.
Adding the new condictions for testing some process in the OpenCV Module.