Update styled-components to the latest version 🚀 (#149)

* fix(package): update styled-components to version 2.4.0

* chore(package): update lockfile

https://npm.im/greenkeeper-lockfile

Author: greenkeeper[bot]

package-lock.json

@@ -106,7 +106,7 @@
     "react-fela": "^6.0.5",
     "react-icons": "~2.2.5",
     "react-jss": "~8.0.0",
-    "styled-components": "~2.3.0",
+    "styled-components": "~2.4.0",
     "styletron": "~3.0.0-rc.3",
     "styletron-react": "~3.0.0-rc.3",
     "webfontloader": "~1.6.28",

package.json

@@ -6992,15 +6992,14 @@ style-loader@^0.19.0:
     loader-utils "^1.0.2"
     schema-utils "^0.3.0"
 
-styled-components@2.3.0:
-  version "2.3.0"
-  resolved "https://registry.yarnpkg.com/styled-components/-/styled-components-2.3.0.tgz#d9cf4574e140fea6426e48632ed0ca4494537718"
+styled-components@2.4.0:
+  version "2.4.0"
+  resolved "https://registry.yarnpkg.com/styled-components/-/styled-components-2.4.0.tgz#086d0fd483d54638837fca3ea546a030b94adf75"
   dependencies:
     buffer "^5.0.3"
     css-to-react-native "^2.0.3"
     fbjs "^0.8.9"
     hoist-non-react-statics "^1.2.0"
-    is-function "^1.0.1"
     is-plain-object "^2.0.1"
     prop-types "^15.5.4"
     stylis "^3.4.0"