Add simple depends_on API.

recipes/engine_tests/bad_properties.py

+from recipe_engine.recipe_api import Property
+from recipe_engine import config
+
+DEPS = [
+    'recipe_engine/properties',
+]
+
+PROPERTIES = {}
+
+RETURN_SCHEMA = config.ReturnSchema(
+    result=config.Single(int),
+)
+
+def RunSteps(api):
+  res = api.depend_on('engine_tests/bottom', {'number': 'lalala'})
+  return RETURN_SCHEMA(result=res['number_times_two'])
+
+def GenTests(api):
+  yield (
+      api.test('basic') +
+      api.properties() +
+      api.expect_exception('TypeError')
+  )