Added optional passing of one or multiple environment variables via --env flag to the bonobo cli.

tests/util/get_passed_env.py

@@ -0,0 +1,22 @@
+import os
+
+from bonobo import Graph
+
+
+def extract():
+    env_test_user = os.getenv('ENV_TEST_USER')
+    env_test_number = os.getenv('ENV_TEST_NUMBER')
+    env_test_string = os.getenv('ENV_TEST_STRING')
+    return env_test_user, env_test_number, env_test_string
+
+
+def load(s: str):
+    print(s)
+
+
+graph = Graph(extract, load)
+
+if __name__ == '__main__':
+    from bonobo import run
+
+    run(graph)