Fix bookmark of URLs with env

For some reason, we'd always reset the env to the first available
once listing available envs, discarding the selection from the URL.
Fix it.

Fixes #3

pulpstatus/js-src/app-body.tsx

@@ -220,9 +220,14 @@ export class AppBody extends React.Component<{}, AppBodyState> {
     }
 
     onEnvsFetched(envs: Array<string>) {
+        const selectedEnv =
+            (this.state.env && envs.indexOf(this.state.env) != -1)
+            ? this.state.env
+            : envs[0];
+
         this.setState({
             availableEnvs: envs,
-            env: envs[0],
+            env: selectedEnv,
         });
         this.startTimer();
         this.fetchData();