fix: tox config file as in sub directory correcting WORKDIR

[saikiran2603]

Signed-off-by: saikiran neo2603@gmail.com

Tox config is not in the directory from where tox command is executed, moved WORKDIR change which was happening before test to after , this ensures tox executes from inside the function folder.

Description

moved WORKDIR command after the test execution , modified copy and chown command to execute properly from new WORKDIR

Motivation and Context

helps fix issue #44

• [X] I have raised an issue to propose this change (required)
• [ ] My issue has received approval from the maintainers or lead with the design/approved label

How Has This Been Tested?

tested with creating new function and executing faas build.

Types of changes

• [X] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [X] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [X] I have updated the documentation accordingly.
• [X] I've read the CONTRIBUTION guide
• [X] I have signed-off my commits with git commit -s
• [ ] I have added tests to cover my changes.
• [X] All new and existing tests passed.

[LucasRoesler]

@alexellis this is :shipit: