fix(commands/run): ensure configured client wrapper port is used

Prior to this commit, using `WRAPPER_PORT` and changing it to a users needs
didn't have any effect as

a) the port has never been passed down to the Aragon client
b) Aragon client's script isn't prepared to retrieve values from the environment

This commit ensures that the port is set as an environment variable,
enabling Aragon client to take advantage of it.

Fixes aragon#198

src/commands/run.js

@@ -288,6 +288,7 @@ exports.handler = function ({
               env: {
                 REACT_APP_ENS_REGISTRY_ADDRESS: ctx.ens,
                 BROWSER: 'none',
+                REACT_APP_PORT: WRAPPER_PORT
               }
             }
 
@@ -353,7 +354,7 @@ exports.handler = function ({
     ${chalk.bold('DAO address')}: ${ctx.daoAddress}
 
     ${(client !== false) ?
-      `Opening http://localhost:3000/#/${ctx.daoAddress} to view your DAO` :
+      `Opening http://localhost:${WRAPPER_PORT}/#/${ctx.daoAddress} to view your DAO` :
       `Use "aragon dao <command> ${ctx.daoAddress}" to interact with your DAO`
     }`)