Adapt intro README to ECon 2013
Adapt exercise 1 README

- use kepler M6
- remove workarounds for m2e bug and not self-
  contained e4 product
Adapt exc 2 to Econ 2013

remove workarounds for m2e bug and
junit 4 bundle version.
Adapt exc3 to Econ 2013
Adapt exc 4 to ECon 2013
correct repository zip name
Adapt exc 5