Update source-map dependency

[nikolay-borzov]

• Update source-map to 0.7.3
• Update dependencies
• Add chai-as-promised to test async functions
• Move types outside types.d.ts since TypeScript generates type definitions
• Give variables more explicit names
• Make explore async
• Always set bundleName in the explore result
• Create ExploreErrorResult during batch processing so that error can be reported later
• Leverage snapshot testing for explore tests

Resolves (#100)