Add a config object

- add the following file:
  + src/urban_meal_delivery/_config.py
- a config module is created holding two sets of configurations:
  + production => against the real database
  + testing => against a database with test data
- the module is "protected" (i.e., underscore) and imported at the
  top level via a proxy-like object `config` that detects in which of
  the two environments the package is being run

poetry.lock

@@ -804,6 +804,17 @@ pytest = ">=4.6"
 [package.extras]
 testing = ["fields", "hunter", "process-tests (2.0.2)", "six", "pytest-xdist", "virtualenv"]
 
+[[package]]
+category = "main"
+description = "Add .env support to your django/flask apps in development and deployments"
+name = "python-dotenv"
+optional = false
+python-versions = "*"
+version = "0.14.0"
+
+[package.extras]
+cli = ["click (>=5.0)"]
+
 [[package]]
 category = "dev"
 description = "World timezone definitions, modern and historical"
@@ -1140,7 +1151,7 @@ optional = ["pygments", "colorama"]
 tests = ["pytest", "pytest-cov", "codecov", "scikit-build", "cmake", "ninja", "pybind11"]
 
 [metadata]
-content-hash = "beb356287b912e1ce67c5997bd4d683dbc424ee24660a93d8f1fb4e511972762"
+content-hash = "862a0bc650dab485af541f185ed3c1e86a8947e7518c8fbcacfd19d5b8055af5"
 lock-version = "1.0"
 python-versions = "^3.8"
 
@@ -1526,6 +1537,10 @@ pytest-cov = [
     {file = "pytest-cov-2.10.0.tar.gz", hash = "sha256:1a629dc9f48e53512fcbfda6b07de490c374b0c83c55ff7a1720b3fccff0ac87"},
     {file = "pytest_cov-2.10.0-py2.py3-none-any.whl", hash = "sha256:6e6d18092dce6fad667cd7020deed816f858ad3b49d5b5e2b1cc1c97a4dba65c"},
 ]
+python-dotenv = [
+    {file = "python-dotenv-0.14.0.tar.gz", hash = "sha256:8c10c99a1b25d9a68058a1ad6f90381a62ba68230ca93966882a4dbc3bc9c33d"},
+    {file = "python_dotenv-0.14.0-py2.py3-none-any.whl", hash = "sha256:c10863aee750ad720f4f43436565e4c1698798d763b63234fb5021b6c616e423"},
+]
 pytz = [
     {file = "pytz-2020.1-py2.py3-none-any.whl", hash = "sha256:a494d53b6d39c3c6e44c3bec237336e14305e4f29bbf800b599253057fbb79ed"},
     {file = "pytz-2020.1.tar.gz", hash = "sha256:c35965d010ce31b23eeb663ed3cc8c906275d6be1a34393a1d73a41febf4a048"},