Use ethcore_dappsPort when constructing URLs (#3139)

* Upon connect, retrieve the available api ports

* Update dapps to load from dappsPort

* Update dapps summary with dappsPort

* Allow proxy to use dappsPort

* Replace /api/ping with HEAD /

* Dynamic port for available apps

* Retrieve content images with dappsPort

* Fix /

* Transfer token dropdown image fix

* IdentityIcon loads images via contentHash

* Update apps fetch to cater for dev & prod

* DRY up 127.0.0.1:${dappsPort} with ${dappsUrl}

js/src/modals/Transfer/Details/details.js

@@ -123,7 +123,13 @@ export default class Details extends Component {
       .map((balance, index) => {
         const token = balance.token;
         const isEth = index === 0;
-        const imagesrc = token.image || images[token.address] || imageUnknown;
+        let imagesrc = token.image;
+        if (!imagesrc) {
+          imagesrc =
+            images[token.address]
+              ? `${api.dappsUrl}${images[token.address]}`
+              : imageUnknown;
+        }
         let value = 0;
 
         if (isEth) {