Show description and value on second xls page and in the parameterlist on the resultpage

To do this we need the description in the xml

Implemented in SVN rev 710-711:

Background info: just copy-pasted from the commit messages:

for xreporter:
  * remembering the short description in the report model
  * providing the short description in the step info (for display on output page)
  * if available, the short description is used in the 'natural description' of conditions
  * the short descriptions are also stored in the report store

Note that hence the short-description is not fetched from the database (which would require to define a SQL statement to retrieve it), but rather the description displayed at the moment the user selected it is remembered.

for xreporter-cocoon:
 * in interactions, for params and conditions with a searchlist, submit short description along with value
 * in HTML & Excel/POI output: use the description instead of the value
 * fixed binary mime type for the interaction.js

Just FYI: the short-description's are also part of the persistent URLs (which basically contain the same information as the stored reports).