imported 25 definitions from typescript-node-definitions

first batch: the easy pickings

- as per https://github.com/borisyankov/DefinitelyTyped/issues/115
- added DT headers (scraped creators from git history)
- added tests
- some modifications
- added CONTRIBUTORS.md for the substantial defs (>50 LOC)
imported Request definitions from typescript-node-definitions

- as per https://github.com/borisyankov/DefinitelyTyped/issues/115
- added DT header (scraped creators from git history)
- added tests
- updated some fields
- restructured to be more accurate
Merge pull request #2084 from borisyankov/import/node

batch of imported defs from typescript-node-definition (25 +1)