UI: image renaming

* FIX Screenshot of ROOT browser (closes #202)
UI: use translated collection names

* (closes #206)
UI: records: file desc + preview only with .ig

* templates: real file descriptions (closes #204)
* Event preview in derived datasets shows only if “.ig” files exist
(closes #164)
templates: CMS Physics Objects link fix

* Fixes links to CMS Physics Objects page.
  (addresses #153) (addresses #198)

* In addition, removes `^L` and `^K` characters in the text.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>