Add emulator to device metadata (#245)

sdk/src/main/java/com/bugsnag/android/DeviceData.java

@@ -90,6 +90,7 @@ public void toStream(@NonNull JsonStream writer) throws IOException {
             .name("locale").value(locale)
             .name("screenDensity").value(screenDensity)
             .name("dpi").value(dpi)
+            .name("emulator").value(isEmulator())
             .name("screenResolution").value(screenResolution);
 
         writer.name("cpuAbi").beginArray();
@@ -109,6 +110,18 @@ void setId(@Nullable String id) {
         this.id = id;
     }
 
+    /**
+     * Guesses whether the current device is an emulator or not, erring on the side of caution
+     *
+     * @return true if the current device is an emulator
+     */
+    private boolean isEmulator() {
+        String fingerprint = Build.FINGERPRINT;
+        return fingerprint.startsWith("unknown")
+            || fingerprint.contains("generic")
+            || fingerprint.contains("vbox"); // genymotion
+    }
+
     /**
      * The screen density scaling factor of the current Android device
      */