labels of disabled and non-disabled material-input multiline component behave in the same way

[ghost]

Both disabled and non-disabled components behave in the same way and it is hard to distinguish between the both.

When a component is disabled it should not check and display requiredErrorMsg until the component is enabled again.

Also floating label should not change it's default position since disabled component is not accepting any input.

Component code:

    <div style="padding: 10px;">
            <material-input [disabled]="true"
                            floatingLabel
                            multiline
                            rows="4"
                            required
                            requiredErrorMsg="Message is empty!"
                            label="Enter a message to send">
            </material-input>

            <material-input [disabled]="false"
                            floatingLabel
                            multiline
                            rows="4"
                            required
                            requiredErrorMsg="Message is empty!"
                            label="Enter a message to send">
            </material-input>
        </div>

angular_components: version: "0.13.0"