Bug fixes and a few new features

- SHSPhoneLogic bugfix: when user try to delete prefix (when it was set) with empty phone number, textfield adds prefix digits (without last digit) to phone number. This happens when prefix contains more then 1 digit.
- SHSNumberFormatter: added method to read formats from predefined configuration array, It helps to read configuration when using .plist to store phone formats.
- SHSNumberFormatter: resetFormats preserves default pattern from changing, so you don't need to set custom default format every time you want to reset added formats. To reset default format user should call resetDefaultFormat or cnage it via setDefaultOutputPattern.
- SHSPhoneTextField: added method to return phone number without format and prefix