add migration for restoring fields in standards
add able to set restoring fields in standards when copies from public standards
add action 'restore' for standards controller
add flashes for action restore in standards controller
able to set previous version
change some functional, add link to restore
add comments
Merge branch 'feature/restoring_standards' into develop

* feature/restoring_standards:
  add comments
  change some functional, add link to restore
  able to set previous version
  add flashes for action restore in standards controller
  add action 'restore' for standards controller
  add able to set restoring fields in standards when copies from public standards
  add migration for restoring fields in standards