merge commit, applied changes from develop
changed style
changed helper for sorting
change view file of study requests, added filtration
moved slider in upper block
Merge branch 'feature/87-change-slider-style-on-main-page' into staging

* feature/87-change-slider-style-on-main-page:
  moved slider in upper block
  change view file of study requests, added filtration
  changed helper for sorting
  changed style
  merge commit, applied changes from develop