Fix dependency on `org.junit4`.

In Kepler, there's only one bundle, `org.junit`.
(cherry picked from commit 1cc62c45be791695e97665406d997416a35d05f1)

And removed reference to junit from sdt.core.
Removes references to JavaStringAutoIndentStrategy

This is an internal JDT class, and its constructor changed between Juno and Kepler.
It was a blocker to be able to use the same build on both Juno and Kepler.
Less non-API reference is better.

The features lost are the one defined in the 'In string literals' in
Preferences>Java>Edito>Typing. They are about managing multiline content in simple string literals.
They didn't really make in the Scala context, where multiline string literals can be used.
(cherry picked from commit a70a5348e25f4334566a6fbeee79b9f12e2791fd)
Merge pull request #461 from skyluc/3.0.x-juno-compatible-kepler

3.0.x juno compatible kepler