Update dependencies

[mapsam]

Updates all critical severity dependencies (or parents thereof) according to dependabot https://github.com/mapbox/dyno/security/dependabot?q=is%3Aopen+sort%3Aseverity

• update documentationjs to latest version, this changes the output in API.md slightly, but content is all there
• update eslint to latest, this comes with a number of critical child dependencies that are updated
• remove coveralls - we aren't uploading coverage anywhere, this can be viewed after running tests with npm run coverage
• update nyc
• update minimist
• update underscore
• remove env from travis file #153
• update Buffer() to Buffer.from() per nodejs deprecation warnings
• update tests to support TableId in the CLI importer function, and remove it before asserting on expected table descriptions