Add additional SQLExceptions to the QueryException output

Fixes #1007

When JRE6 is used, it adds an extra Exception with additional information.
When JRE7 is used, it adds the extra SQLExceptions as suppressed exceptions.
Correctly get the linked SQLExceptions
Separate the individual exceptions with a blank line
Remove the {@literal } wrapping in the JavaDoc
Cleanup of the added unique constraint after the test
Add another batch in the H2ExceptionSuiteTest
Add support for access to the used Java version in tests
Add specific asserts for Java 6 and 7
Change author tag in JavaDoc
Add the simple exception creation case to the ExceptionSuiteTest
Merge pull request #1008 from querydsl/sqlexception

Add additional SQLExceptions to the QueryException output