Add NASDAQ Company and ETF lists

test/tasks/test_nasdaq.py

@@ -0,0 +1,17 @@
+from unittest import TestCase
+
+from metrik.tasks.nasdaq import NasdaqCompanyList, NasdaqETFList
+
+
+class NasdaqTest(TestCase):
+
+    def test_company_list(self):
+        companies = NasdaqCompanyList.retrieve_data()['companies']
+        assert len(companies) > 6000
+        # TODO: Get lists of companies from ETF holdings and verify that they
+        # can be found here as well - this should be a superset
+
+
+    def test_etf_list(self):
+        etfs = NasdaqETFList.retrieve_data()['etfs']
+        assert len(etfs) > 1500