Merge pull request #39 from OpenZeppelin/fix/remove-ethpm

Remove ethpm.json

ethpm.json

-{
-  "package_name": "zeppelin",
-  "version": "2.1.3",
-  "description": "Secure Smart Contract library for Solidity",
-  "authors": [
-    "OpenZeppelin Community <maintainers@openzeppelin.org>"
-  ],
-  "keywords": [
-    "solidity",
-    "ethereum",
-    "smart",
-    "contracts",
-    "security",
-    "zeppelin"
-  ],
-  "license": "MIT"
-}