Update some dependencies.

Author: selaux

package.json

@@ -7,13 +7,13 @@
         "async": "1.2.0",
         "bin-pack": "1.0.1",
         "glob": "5.0.10",
-        "jimp": "0.2.19",
+        "jimp": "0.2.21",
         "mkdirp": "0.5.1",
-        "underscore": "1.8.2"
+        "underscore": "1.8.3"
     },
     "optionalDependencies": {
-        "canvas": "1.3.0",
-        "gm": "1.21.1"
+        "canvas": "1.3.12",
+        "gm": "1.22.0"
     },
     "devDependencies": {
         "chai": "2.1.1",