Add getSimpleTypeObject(Class parameter, String text) method to org.apache.axis2.databinding.typemapping.SimpleTypeMapper

Currently org.apache.axis2.databinding.typemapping.SimpleTypeMapper class has getSimpleTypeObject(Class parameter, OMElement value) method. Only usage of the OMElement parameter of this method is to retrieve the text encapsulated in it by calling value.getText() method. getSimpleTypeObject(Class parameter, String text) would be a more API-wise cleaner version of this method.

Introducing getSimpleTypeObject(Class parameter, String text) is useful since converting a String into a simple type (int, long, etc.) is a common requirement. In fact, in many places of Apache Synapse project this sort of conversions are done using newly written code. If getSimpleTypeObject(Class parameter, String text) method is introduced to SimpleTypeMapper class, then it can be reused by number of places including some code in Apache Synpase project without writing new code for the same purpose.