Remove buttons resize in small devices

The bottons don't resize anymore in small screns when hovered
or activated.
Merge branch 'master' into feat/design_improvement

Conflicts:
	traintool/src/frontend/dependencies/assets/sass/screen.scss
Add rules for events in css

Add a more complete set of css rules for the differents events
in the css and limit the number of listed exercises in the typeahead
to 5.
Hotifx: Readd images

Readd the images removed after the merge with the feat/design_improvement.
Merge branch 'master' of github.com:AEHO/traintool