Merge pull request #1 from mandx/minor-exception-improvements

Simple exception hierarchy and raise the corresponding exceptions for 403 and 404 responses
Merge pull request #2 from mandx/minor-type-conversion

Convert to `int` the result of the DU action
Merge pull request #7 from mandx/develop

Develop - Updating from upstream repo
Added simple script to stress-test the NetStorage REST service
Merge branch 'develop' into stress-testing