Added test_verify_changed_source_file test to flag up the issue mentioned in Bug #1354880
Added in tests including compare_data
move netloc usage definitions into respective backends
  - Tests to validate that duplicity does not check filesystem source during
    verify unless --compare-data is specified
* Merge in lp:~ed.so/duplicity/move_netloc
  - move netloc usage definitions into respective backends
  - fix "[Question #259173]: rsync backend fails"
    https://answers.launchpad.net/duplicity/+question/259173