Readme: Change build status from PNG to SVG icon
Readme: Change build status from PNG to SVG icon

Also add devDependency badge and change to Coveralls badge for icon (but link to codecov.io)

OpenSprinkler/OpenSprinkler-App,OpenSprinkler/OpenSprinkler-App,PeteBa/OpenSprinkler-App,PeteBa/OpenSprinkler-App,PeteBa/OpenSprinkler-App,OpenSprinkler/OpenSprinkler-App