Fix travis, bump deps

.travis.yml

@@ -3,9 +3,17 @@ node_js:
   - "0.10"
   - "0.12"
   - "iojs"
+  - "4"
 sudo: false
 addons:
   firefox: "34.0"
+  apt:
+    sources:
+      - ubuntu-toolchain-r-test
+    packages:
+      - g++-4.8
+env:
+  - CXX=g++-4.8
 notifications:
   email:
     on_success: never

package.json

@@ -50,10 +50,10 @@
   },
   "dependencies": {
     "elliptic": "^5.0.0",
-    "es6-promise": "^2.0.1",
+    "es6-promise": "^3.0.2",
-    "nan": "^1.4.1"
+    "nan": "^2.0.9"
   },
   "optionalDependencies": {
-    "secp256k1": "~0.0.15"
+    "secp256k1": "^1.1.4"
   }
 }