Add methods to custom background color ...

[ainopara]

and custom the attributes of text in string picker as an example.
Use them like this:

    ActionSheetStringPicker *picker = [[ActionSheetStringPicker alloc] initWithTitle:@"" rows:array initialSelection:1 doneBlock:nil cancelBlock:nil origin:self.pageLabel];
    picker.pickerBackgroundColor = [UIColor blackColor];
    picker.pickerTextAttributes = @{NSForegroundColorAttributeName: [UIColor whiteColor],
                                    NSFontAttributeName:[UIFont systemFontOfSize:21.0],};
    [picker showActionSheetPicker];

This PR will close #58, fix #102

[skywinder]

@ainopara Wow, awesome! Can you also add some example usage of new method to Example project?

[skywinder]

This PR will close #58

[ainopara]

Example updated. It seems custom font attribute will be reset by system.

[ainopara]

I don't know how to fix the CI build failure this time.

[skywinder]

@ainopara yes it's common issue with frameworks. Try to merge my PR. It should help.

[skywinder]

@ainopara ok, don't worry, I will handle this failure.

[ainopara]

^_^
Thanks.

[skywinder]

@ainopara Thank you! BDW: fixed according this: http://stackoverflow.com/a/27614914/1698467