bring leveldown down

Author: daviddias

package.json

@@ -63,7 +63,7 @@
  "debug": "^3.1.0",
  "ipfs-block": "~0.6.0",
  "level-js": "timkuijsten/level.js#idbunwrapper",
- "leveldown": "^2.0.0",
+ "leveldown": "^1.7.2",
  "lock-me": "^1.0.3",
  "lodash.get": "^4.4.2",
  "lodash.has": "^4.5.2",