Added findBy method and adjusted test message for existing findAllBy

Added findBy beneath find method.
It enables to build where clauses in the same way of findAllBy.
Some messages for test code for findAllBy may be confusing after addition of findBy,
so adjusted to make clear to findAllBy is the kind of *All method.
Merge pull request #330 from diceit/spike4/findBy

Added findBy method and adjusted test message for existing findAllBy