config refactor (#1854)

* split out config

* add tests for base and app config, refactor client config out of app config

* refactor default config retrieval

* create config test class and helper functions

* move default_config into server to fix import issue

server/test/unit/data_common/test_matrix_loader.py

@@ -4,7 +4,7 @@ import tempfile
 import time
 import unittest
 
-from server.common.app_config import AppConfig
+from server.common.config.app_config import AppConfig
 from server.common.errors import DatasetAccessError
 from server.data_common.matrix_loader import MatrixDataCacheManager
 from server.test import FIXTURES_ROOT
@@ -38,7 +38,7 @@ class MatrixCacheTest(unittest.TestCase):
         result = {}
         for k, v in datasets.items():
             # filter out the dirname and the .cxg from the name
-            newk = int(k[1][len(dirname) + 1: -4])
+            newk = int(k[1][len(dirname) + 1 : -4])
             result[newk] = v
 
         return result