Meridiem Selector & clock button appear editable when read-only="true"

[cbacon91]

When the meridiem selector is available but the directive is marked as read-only, the user can still click on the meridiem selector, but not make any choices. It would look better if this was not clickable at all - md-select has a disabled option to disable this.

Additionally, when the directive is in read-only, the clock icon has cursor: pointer, even though it's not editable. This should probably be set to cursor: default to stay consistent with md-datepicker.

Codepen of the issues:

https://codepen.io/cbacon91/pen/wqBrgY

[Andreasbaaserud]

Good points, I will apply the fixes below for release 1.0.8

• [ ] Append ng-disabled to md-select in mdMeridiem directive, no need for ng-disabled on md-option element
• [ ] set cursor: default when directive is in read-only