Java example code for Getting Started

* WiP on Java version of new Hello World

Done:
- implementation for first 3 sections
- tests for first 2 sections

To do:
- formatting
- tests for section 3
- section 4 and 5
- hooking the fragments into the docs themselves

* Finish tutorial_03 conversion

* Converted tutorial 04

* Convert step 5 scala->java

* Reformat Java code (thx IntelliJ IDEA)

* Format using 2 spaces

Really it'd be neat to have something like scalariform for the Java code, too

* Make fields 'private final'

* Make message classes 'public static final'

* Use primitive long/double where possible

* sender() -> getSender()

* Static import of org.junit.Assert....

* Final actor fields

* println() the instruction to hit ENTER to quit

* Use jdocs package for quickstart, too

* Use helper methods for message handling

* Compare doubles specifying a delta

* Keep tutorial steps independent

akka-docs-new/src/test/java/jdocs/tutorial_2/DeviceInProgress.java

@@ -0,0 +1,26 @@
+package jdocs.tutorial_2;
+
+import java.util.Optional;
+
+import jdocs.tutorial_2.Device.ReadTemperature;
+import jdocs.tutorial_2.Device.RecordTemperature;
+import jdocs.tutorial_2.Device.RespondTemperature;
+import jdocs.tutorial_2.Device.TemperatureRecorded;
+
+class DeviceInProgress1 {
+
+  //#read-protocol-1
+  public static final class ReadTemperature {
+  }
+
+  public static final class RespondTemperature {
+    final Optional<Double> value;
+
+    public RespondTemperature(Optional<Double> value) {
+      this.value = value;
+    }
+  }
+  //#read-protocol-1
+
+}
+