Add user finder.

src/components/user_finder/user_finder.js

@@ -0,0 +1,18 @@
+const UserFinder = {
+  data: () => ({
+    username: undefined
+  }),
+  methods: {
+    findUser (username) {
+      this.$store.state.api.backendInteractor.externalProfile(username)
+        .then((user) => {
+          if (!user.error) {
+            this.$store.commit('addNewUsers', [user])
+            this.$router.push({name: 'user-profile', params: {id: user.id}})
+          }
+        })
+    }
+  }
+}
+
+export default UserFinder