Make updateTabStyles() callable from CustomTabProvider (fixes #68).

[Nutomic]

This lets me have the default tab style, and make changes to it without re-implementing everything.

Here's my getCustomTabView() implementation (I pass the PagerSlidingTabStrip to my PagerAdapter in the constructor):
@OverRide
public View getCustomTabView(ViewGroup viewGroup, int i) {
TextView tv = (TextView) LayoutInflater.from(mContext).inflate(R.layout.psts_tab, viewGroup, false);
mTabStrip.updateTabStyle(tv);
tv.setText(getPageTitle(i));
// apply my costumizations

    // HACK: Remove ID so text color is not changed on tab switch.
    tv.setId(0);
    return tv;
}

As you see, this isn't quite perfect because of the hack I need, but it works for me. I'm open for any improvements ;)

[jpardogo]

Thanks for the PR I will review it asap

[jpardogo]

I added a new solution to #68, let me know what you think. I think this one is hacky I would prefer to find another way but many thanks for the PR