Add .is-vertically-paddingless and other class helpers (#943)

sass/base/helpers.sass

@@ -145,9 +145,25 @@ $displays: 'block' 'flex' 'inline' 'inline-block' 'inline-flex'
 .is-marginless
   margin: 0 !important
 
+.is-vertically-marginless
+  margin-top: 0 !important
+  margin-bottom: 0 !important
+
+.is-horizontally-marginless
+  margin-left: 0 !important
+  margin-right: 0 !important
+
 .is-paddingless
   padding: 0 !important
 
+.is-vertically-paddingless
+  padding-top: 0 !important
+  padding-bottom: 0 !important
+
+.is-horizontally-paddingless
+  padding-left: 0 !important
+  padding-right: 0 !important
+
 .is-radiusless
   border-radius: 0 !important