Remove unused dependencies (#250)

package.json

@@ -70,7 +70,6 @@
     "email-validator": "^1.0.7",
     "fs-promise": "^1.0.0",
     "glob": "^7.1.1",
-    "graceful-fs": "^4.1.11",
     "ignore": "^3.2.0",
     "ini": "^1.3.4",
     "is-url": "^1.2.2",
@@ -82,9 +81,7 @@
     "progress": "^1.1.8",
     "psl": "^1.1.15",
     "resumer": "^0.0.0",
-    "semver-compare": "^1.0.0",
     "socket.io-client": "^1.7.2",
-    "spdy": "^3.4.4",
     "split-array": "^1.0.1",
     "text-table": "^0.2.0",
     "tmp-promise": "^1.0.3",
@@ -93,8 +90,6 @@
   "devDependencies": {
     "alpha-sort": "^2.0.0",
     "ava": "^0.17.0",
-    "del": "^2.2.2",
-    "estraverse-fb": "^1.3.1",
     "pkg": "^3.0.0-beta.22",
     "xo": "^0.17.1"
   }