Started documentation of lendingview
Finished documentation of lending view.
Finished documentation of return view.
Refactored and corrected lending and return view.
Merge remote-tracking branch 'origin/develop' into develop

Conflicts:
	src/main/java/de/dhbw/humbuch/view/LendingView.java
	src/main/java/de/dhbw/humbuch/view/ReturnView.java
Merge pull request #617 from henningmu/develop

Documented and Refactored Lending and Return view