Added functionality to a Datasource for deleting a section from the XML

[JustinGrilli]

Summary

In some cases we may want to delete an entire section from a Datasource.
We can utilize the built in del Python syntax to delete a section; i.e. del Datasource.columns

Changes

• Created a function: Datasource.__remove_section_from_parent
  • For removing a section from a parent Element
• Implemented Datasource.__delattr__ to call __remove_section_from_parent
• Replaced repeated code in Datasource.save function to use __remove_section_from_parent
• Added a test for del Datasource.section functionality

Tests

• Used del Datasource.<section>:
  • del datasource.extract
  • datasource.save()
  • Confirmed extract was removed from the XML