ECNA-2014 Code changes in recovery entry points and solution

- Change POMs for Tycho 0.20.0 and new target platform (using the most
  recent milestone Luna M6)
- Submit changes to files generated by the Eclipse e4 Tools (version
  0.14.0.v20140310-0920)
ECNA-2014 Update entry page and exercises 1-3

- Updated versions of the base distributions and update sites used to
  create the Eclipse installation for the tutorial.
- Changed wording and some other details in the introduction and
  exercises 1-3 (because I will presenting these steps for the first
  time).
- Updated screenshots which haven't been updated recently. Now all
  screen shots are made on a PC with a DPI setting of 104 (which is 
  108% of the Windows 7 default).
- Deleted unreferenced images.