Fixes setting of preview server in PreviewManager

* The preview manager is dependent on being notified by its execution
  listener for setting the preview/default server. Thus, the server manager
  must set the default server after the managers have been initialised.

* Only downside is that adding each server internally sets the default
  server and logic exists to avoid setting the default server to the same
  server. This has to be removed but since the setting of the default
  server is not a very common function, it should not be a problem.
Removes the new server action from the Server View action provider

* Since users should be using the JBoss Server new wizard, there is little
  point in having a separate different 'new server wizard'.

* The only remaining place the new server wizard is now used is the guides
  view which is appropriate since it tries to be comprehensive.
TEIIDDES-1819: Flesh out Server management section

* Adds some more explanation to the server management chapter and brings
  up-to-date server images and description.
Merge pull request #223 from phantomjinx/master

Preview Manager fix and documentation