title: Firebase RemoteConfigSettings doesn't reflect minimumFetchInterval changes
body: <p>I'm trying to change the <code>minimumFetchInterval</code> for my <code>RemoteConfigSettings</code>. I set the value to 0 but the value doesn't update. As a workaround, I can create a new <code>RemoteConfigSettings</code> object, set the value there, and assign the settings to the <code>remoteConfig</code> instance.</p>
  
  <pre><code>let remoteConfig = RemoteConfig.remoteConfig()
  remoteConfig.configSettings.minimumFetchInterval = 0
  </code></pre>
  
  <p>Reading back <code>minimumFetchInterval</code> still shows the default of 43200.</p>
  
  <p>The header is defined in Obj-C as:
  <code>@property(nonatomic, assign) NSTimeInterval minimumFetchInterval;</code>
  So I would expect the value to reflect assignments.</p>
  
  <p>This does work:</p>
  
  <pre><code>remoteConfig = RemoteConfig.remoteConfig()
  
  let configSettings = RemoteConfigSettings()
  configSettings.minimumFetchInterval = 0
  remoteConfig.configSettings = configSettings
  </code></pre>
  
  <p>I am able to work around this issue, but this should be fixed. Am I missing something, or should I continue to expect these APIs to be incorrect?</p>
  
  <p>The documentation of the <code>RemoteConfigSettings</code> class doesn't even mention the <code>minimumFetchInterval</code> property, but their how to docs do.</p>