Update font family to make design consistent in all platforms (#318)

* Add inter font, remove modal header bg

* Remove unnecessary font files

* Fix codeclimate issues, remove letter-spacing attribute

app/javascript/dashboard/assets/scss/app.scss

@@ -1,3 +1,5 @@
+@import 'shared/assets/fonts/inter';
+
 @import 'variables';
 
 @import '~spinkit/scss/spinners/7-three-bounce';