[JS] Implement random-access file format

[asfimport]

Part of ARROW-541. Create a Javascript interface capable of reading the random-access file format (ARROW-264)

Reporter: Brian Hulette / @TheNeuralBit
Assignee: Brian Hulette / @TheNeuralBit

Related issues:

• [JS] Implement JavaScript-compatible implementation (Is contained by)

_{Note: This issue was originally created as ARROW-613. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 358
#358