Added measurement, readout and readout_value models

commands:
rails generate redmine_plugin_model body_tracking measurement
name:string hidden:boolean source:references
rails generate redmine_plugin_model body_tracking readout
measurement:references quantity:references unit:references
rails generate redmine_plugin_model body_tracking readout_value
readout:references value:decimal taken_at:timestamp

test/unit/measurement_test.rb

@@ -0,0 +1,9 @@
+require File.expand_path('../../test_helper', __FILE__)
+
+class MeasurementTest < ActiveSupport::TestCase
+
+  # Replace this with your real tests.
+  def test_truth
+    assert true
+  end
+end

test/unit/readout_test.rb

@@ -0,0 +1,9 @@
+require File.expand_path('../../test_helper', __FILE__)
+
+class ReadoutTest < ActiveSupport::TestCase
+
+  # Replace this with your real tests.
+  def test_truth
+    assert true
+  end
+end

test/unit/readout_value_test.rb

@@ -0,0 +1,9 @@
+require File.expand_path('../../test_helper', __FILE__)
+
+class ReadoutValueTest < ActiveSupport::TestCase
+
+  # Replace this with your real tests.
+  def test_truth
+    assert true
+  end
+end