refactor(ripple): adds support for non-fixed tabs

Closes #825.
Closes #460.
How do `Transitions for content changes` affect inkBar colors? 
Also I was looking in tabs-theme.scss, we support  ripple color but not an inkBar color. 

```cs
md-tab {
  .md-ripple-container {
      color: $tabs-highlight-color;
  }
}
```
Should we add that to be clear and allow specific customizations?