intrinsicContentSize does not behave like UIPageControl

[hpique]

Thanks for open sourcing this component.

I noticed that SMPageControl intrinsicContentSize does not behave like UIPageControl.

In particular, it returns UIViewNoIntrinsicMetric for the width whereas UIPageControl calculates a width based on the number of pages.

Without this, SMPageControl is not a drop in replacement for UIPageControl.

[bejo]

I just fixed it in my fork: #29

Please let me know if it works fine for you. (it does for me, but... this fix seems like was almost too easy :)