Loan service layer implementation

LoanDao.java
- small fixes in javadoc

ServiceDataAccessException.java
- classname typo fix (missing double s, Acces -> Access)

BookServiceImpl.java
- ServiceDataAccessException classname change

CustomerServiceImpl.java
- ServiceDataAccessException classname change

LoanService.java
- new interface for loan service layer

LoanServiceImpl.java
- new implementation of LoanService interface

EntityConvertor.java
- added methods for Loan<->LoanTO conversion

BookServiceTest.java
- ServiceDataAccessException classname change

CustomerServiceTest.java
- ServiceDataAccessException classname change
Merge branch 'master' of https://github.com/xklech/PA165_library.git
Bugfixes

LoanServiceImpl.java
- added @service annotation & setters for class attributes

LoanTO.java
- method naming conventions fix

EntityConvertor.java
- applied method naming conventions from LoanTO

CustomerServiceTest.java
- minor bugfixes