Remove currently unused devdeps.

package.json

@@ -18,10 +18,6 @@
         "underscore": "1.3.x",
         "zfs": "*"
     },
-    "devDependencies": {
-        "mocha": "*",
-        "should": "*"
-    },
     "repository": {
         "type": "git",
         "url": "git://github.com/calmh/zsnapper.git"