Restore classes that are deprecated for 6 years

This reverts commit 745ca05dccf5cc907e43a58142bb8be97da2b78f. The
deletion of the classes caused some problems for users (see
https://groups.yahoo.com/neo/groups/junit/conversations/topics/24572).

In addition, the new coding style has been applied and "major" has
been added to the deprecation messages in the Javadoc.