collections: standardisation on plural forms

* Standardises all collection names to plural forms such as "Datasets"
  and "Analyses".  (closes #118)

* Amends views, templates, fixtures accordingly.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
CMS: new tools record describing event displays

* Adds new record to CMS Tools collection describing event display
  tools.  (addresses #34) (addresses #126) (addresses #58)

* Merge note: installation instructions amended accordingly.

Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
CMS: new collection of Validated Runs

* Adds new collection "CMS Validated Runs".  Not attached in the
  collection tree anywhere so that it remains "hidden".  (addresses #34)

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
CMS: new record for Validated Runs

* Adds new record for "CMS Validated Runs" collection.
  (addresses #34) (PR #123)

* Merge note: installation instructions amended accordingly.

Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
records: changes in Primary Datasets
collections: introducing description

* introduced collection description on collection/<collection> (close
#117)
UI: "about" pages + "news" page updated

* (addresses #126)
* added CMS/ALICE statements as news