upgrade dependences

package.json

@@ -18,7 +18,7 @@
   ],
   "license": "MIT",
   "dependencies": {
-    "accepts": "^1.1.0",
+    "accepts": "^1.2.2",
     "co": "^4.1.0",
     "content-disposition": "~0.5.0",
     "cookies": "~0.5.0",
@@ -27,18 +27,18 @@
     "destroy": "^1.0.3",
     "error-inject": "~1.0.0",
     "escape-html": "~1.0.1",
-    "fresh": "~0.2.1",
-    "http-assert": "^1.0.1",
-    "http-errors": "^1.2.0",
+    "fresh": "~0.2.4",
+    "http-assert": "^1.1.0",
+    "http-errors": "^1.2.8",
     "koa-compose": "^2.3.0",
     "koa-is-json": "^1.0.0",
     "media-typer": "~0.3.0",
-    "mime-types": "^2.0.0",
+    "mime-types": "^2.0.7",
     "on-finished": "^2.1.0",
     "only": "0.0.2",
     "parseurl": "^1.3.0",
-    "statuses": "^1.1.0",
-    "type-is": "^1.5.0",
+    "statuses": "^1.2.0",
+    "type-is": "^1.5.5",
     "vary": "^1.0.0"
   },
   "devDependencies": {