add coverage report
Merge pull request #8 from hybridgroup/429-add-coverage-report

add coverage report
Fix face detection example
Update commands to match new Driver format

- removed `display_video` from Camera driver, was not a function
- removed `show_image` and `delay` from Window driver, were not functions
Update .travis.yml
Merge pull request #9 from hybridgroup/update/commands

Update commands to match new Driver format
Bump version to "0.8.0"