Near handler

[YunPearce]

Closes #2 .
%near-handler agent, with implemented spec from #2 .

[hanfel-dovned]

Our spec for %near-handler will likely change now that we know more about userspace permissions, but this work so far definitely fulfills #2 and will act as a good foundation for that.

Will merge this once the check gets fixed, @SuperCoolYun see this error message:

The dist/index.js seems to be stale. Please run *yarn build* and commit the dist/index.js file.