Cache results of Concerto version check.  Closes #559.
Fix cache check. #559
Fix pagination with many children, close #537.
Merge branch 'master' of github.com:concerto/concerto
Use Rails caching middleware for version check per #559
Removed old icon sprites and sprites.scss.erb; created Concertocons icon font for logo button and other headers to close #259; introduced future content header icon to close #430
Merge branch 'master' into rails-4

* master:
  Removed old icon sprites and sprites.scss.erb; created Concertocons icon font for logo button and other headers to close #259; introduced future content header icon to close #430
  Use Rails caching middleware for version check per #559
  Fix pagination with many children, close #537.
  Fix cache check. #559
  Cache results of Concerto version check.  Closes #559.