Refactor browser dropdown links and components (#5562)

* refactor browser links and about modal

Moved about modal to separate component and added unit tests.

* refactor change password modal component

* added unit tests for ChangePasswordModal

* fix logout function in browser dropdown

* remove older unused BrowserDropdown component

* remove unused variables from BrowserDropdown component

* show BrowserDropdown and StorageInfo only for LoggedIn users

Non-loggedIn users will see a 'Login' button

browser/app/js/browser/InputGroup.js

@@ -0,0 +1,70 @@
+/*
+ * Minio Cloud Storage (C) 2016, 2018 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import React from "react"
+
+let InputGroup = ({
+  label,
+  id,
+  name,
+  value,
+  onChange,
+  type,
+  spellCheck,
+  required,
+  readonly,
+  autoComplete,
+  align,
+  className
+}) => {
+  var input = (
+    <input
+      id={id}
+      name={name}
+      value={value}
+      onChange={onChange}
+      className="ig-text"
+      type={type}
+      spellCheck={spellCheck}
+      required={required}
+      autoComplete={autoComplete}
+    />
+  )
+  if (readonly)
+    input = (
+      <input
+        id={id}
+        name={name}
+        value={value}
+        onChange={onChange}
+        className="ig-text"
+        type={type}
+        spellCheck={spellCheck}
+        required={required}
+        autoComplete={autoComplete}
+        disabled
+      />
+    )
+  return (
+    <div className={"input-group " + align + " " + className}>
+      {input}
+      <i className="ig-helpers" />
+      <label className="ig-label">{label}</label>
+    </div>
+  )
+}
+
+export default InputGroup