misc: change default indicatorOffset to 10

[hite]

If user don't set indicatorOffset explictly , meanwhile the height of subview of ScrollView is below 250, the indicatorOffset default value will lead to PageControl been disappeared from user's sight.

I think indicatorOffset=10 will avoid to be in such embarrassing situation that i was today.

[tioback]

This solves part of issue #64

[SupriyaKalghatgi]

@hite The workaround that you provided, dd'nt help me