Move, remove & update dependencies

• Remove execa dependency 9d664d6
• Upgrade all minor versions 7ac7e47
• Add np as dev dependency d74e85f
• Bump lodash from 4.17.11 to 4.17.19 (#24) 1d45b6c
• Remove unused dependencies (#26) 5deee38
• Move dependencies to dev-dependencies (#25) 93dfd83

v2.0.0...v2.1.0