Incorrect .radio-inner width/height calculation

[floydspace]

Short description of what this resolves:

Resizing of the radio button icon using $radio-md-icon-width and $radio-md-icon-height variables in Android platform was incorrect. The inner round shifted to the right-bottom position.

Changes proposed in this pull request:

• Fixed width and height calculation of the inner round.

Ionic Version: 2.x

[brandyscarney]

Looks great! Thanks :)