fix(tooltip): change from inline to inline-block to account for md-panel change

- `md-panel` changed from `position: fixed` to `relative`
  - that resulted in the tooltip's `height` style not having any effect

Author: Splaktar

Diff for: src/components/tooltip/tooltip.scss

@@ -9,6 +9,7 @@ $tooltip-lr-padding-sm: 16px !default;
 $tooltip-max-width: 32px !default;
 
 .md-tooltip {
+  display: inline-block;
   pointer-events: none;
   border-radius: 4px;
   overflow: hidden;