Make proxy with zero dependencies (no express, body-parser)

[csantanapr]

Making the web proxy leaner avoids the delay to load module tree for express and body-parser.
Have the web proxy use http server from nodejs

[rabbah]

shedding express would also make startup faster.

[dgrove-oss]

Not done; commented on the wrong issue.

[dgrove-oss]

Closed the wrong issue; reopening.