templates: text corrections in VM Limitations

* Updates Limitations text in VM page.  (closes #156) (PR #166)
records: initial release of JSON data model

* Initial release of JSON data model for the CERN Open Data
  portal.  (closes #93)

* Removes generic `atlantis.cfg`.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
templates: propagation of "issues and limitations"

* Propagates "issues and limitations" metadata information (taken from
  JSON field `documentation_note` aka MARC tag `556`) into various
  detailed record page templates.  (addresses #120)

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
UI: VM routing + added intro + ALICE VM page

* changed VM routing
* added a general page for selection
* updated ALICE VM page
* (closes #116)
UI: updated various pages + switch button

* new tab feature to various pages with General/CMS/ALICE views
* new “about physics” page (close #153)
* updated “About” pages (closes #101)
* updated “Getting Started” page (closes #28)