title: Cannot use scanBleDevices to scan
body: <p>I'm tryig the library for the first time on kotlin, because of that I read that in order to scan first I need to implement it with 
  <code>implementation "com.polidea.rxandroidble2:rxandroidble:1.10.0"</code>, create an RxBleClient and set the scan parameters, but it seems to be a problem with the method scanBleDevices().</p>
  
  <p>I tried the code that appears on the description of the repository and the code from the kotlin example.</p>
  
  <p>With the code from the description, there is only an error on scanBleDevices</p>
  
  <pre><code>rxBleClient = RxBleClient.create(this)
  
  val scanSubscription = rxBleClient.scanBleDevices(
          new ScanSettings.Builder()
              // .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY) // change if needed
              // .setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES) // change if needed
              .build()
          // add filters if needed
  )
      .subscribe(
          {
              // Process scan result here.
          },
          {
              // Handle an error here.
          }
      );
  
  // When done, just dispose.
  scanSubscription.dispose();
  </code></pre>
  
  <p>With the code from the kotlin examples, there is also an error with the Observable that shows <code>No type arguments expected for class Observable</code></p>
  
  <pre><code>private fun scanBleDevices(): Observable&lt;ScanResult&gt; {
          val scanSettings = ScanSettings.Builder()
              .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
              .setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES)
              .build()
  
          val scanFilter = ScanFilter.Builder()
               //.setDeviceAddress("B4:99:4C:34:DC:8B")
              // add custom filters if needed
              .build()
  
          return rxBleClient.scanBleDevices(scanSettings, scanFilter)
  }
  </code></pre>
  
  <p>The problem occurs with the method scanBleDevices() that prompts an alert requesting scanSettings and scanFilter which they have been used it correctly:</p>
  
  <pre><code>None of the following functions can be called with the arguments supplied.
   scanBleDevices(ScanSettings!, vararg ScanFilter!) defined in com.polidea.rxandroidble2.RxBleClient
   scanBleDevices(vararg UUID!) defined in com.polidea.rxandroidble2.RxBleClient
  </code></pre>