DATAJPA-415 - Convert array parameter values to Collection if necessary.

In order to support query methods with array-typed parameters (e.g. parameters passed in as varargs) correctly we have to convert such an array into a collection. Previously we passed those parameters as is which led to Exceptions in EclipseLink and Hibernate, e.g. Hibernate: IllegalArgumentException: Encountered array-valued parameter binding, but was expecting [java.lang.Integer].
DATAJPA-415 - Polishing.

Simplified implementation of ParameterBinder.convertToCollectionIfNecessary(…).

Added a simpler test case for plain query execution and ignored that for EclipseLink and OpenJpa as it fails with both the EclipseLink and OpenJpa versions we currently rely on. See the ignored test cases for links to bug reports.

Original pull request: #45.