Added support for improvement_direction to relevant values, which is propogated to chartjson.

tools/telemetry/telemetry/value/string_unittest.py

Index: tools/telemetry/telemetry/value/string_unittest.py
diff --git a/tools/telemetry/telemetry/value/string_unittest.py b/tools/telemetry/telemetry/value/string_unittest.py
index f629ea0d7b246f06bcdc620752b474226f888b42..ed35239b8e41647ee822af6afa948a47ae23210e 100644
--- a/tools/telemetry/telemetry/value/string_unittest.py
+++ b/tools/telemetry/telemetry/value/string_unittest.py
@@ -115,7 +115,7 @@ class StringValueTest(TestBase):
     v = value.Value.FromDict(d, {})
 
     self.assertTrue(isinstance(v, string.StringValue))
-    self.assertEquals(v.value, 'foo')
+    self.assertEquals('foo', v.value)
 
   def testFromDictNoneValue(self):
     d = {
@@ -123,7 +123,7 @@ class StringValueTest(TestBase):
       'name': 'x',
       'units': 'unit',
       'value': None,
-      'none_value_reason': 'n'
+      'none_value_reason': 'n',
     }
 
     v = value.Value.FromDict(d, {})