Fix upgrade to babel 7

Why:

• Babel 7 has breaking changes.

This change addresses the need by:

• Use a babel config to migrate stage-0 presets for Babel 6 to Babel 7
• Add new babel 7 stage 0 packages to npm install
• Update go runner to run each javascript file through babel as directory information is now lost when outputing to a directory.

Side effects:

• 4x slower as we're running each file through babel separately. It would be a good thing to investigate what the performance would look like if we ran for each directory instead of each file.