Update to CircleCI 2.0 from 1.0

Created a new configuration for CircleCI 2.0 since 1.0 will be disabled
soon.
Tried to mimic the original behaviour as close as possible using the new
configuration.
Currently we only build privacyIDEA using `setup.py` and `make
builddeb-nosign` in order to catch failures in these steps. There is
(currently) no test for functionality!
Also the unit tests won't be run.

.circleci/config.yml

@@ -0,0 +1,50 @@
+version: 2
+jobs:
+  build:
+    docker:
+      # this is a debian based image but this shouldn't be a problem.
+      - image: circleci/python:2.7-stretch
+
+    working_directory: ~/repo
+
+    steps:
+      - checkout
+      - run: git submodule sync
+      - run: git submodule update --init
+        # install some required packages for building ubuntu packages
+      - run: sudo -u root apt-get install build-essential python-setuptools python-all devscripts lsb-release
+
+      # Download and cache dependencies
+      - restore_cache:
+          keys:
+          - v1-dependencies-{{ checksum "requirements.txt" }}
+          # fallback to using the latest cache if no exact match is found
+          - v1-dependencies-
+
+      # Setup the Virtualenv for building/installing privacyidea
+      # We won't use requirements.txt here since we build using setup.py
+      - run:
+          name: install dependencies
+          command: |
+            virtualenv venv
+            . venv/bin/activate
+            pip install sphinx mock sphinxcontrib-httpdomain
+
+      - save_cache:
+          paths:
+            - ./venv
+          key: v1-dependencies-{{ checksum "requirements.txt" }}
+
+      # run builds (currently no tests in CircleCI)
+      - run:
+          name: run setup.py build
+          command: |
+            . venv/bin/activate
+            python setup.py install
+            make builddeb-nosign
+
+      - run:
+          name: run ubuntu package build
+          command: |
+            . venv/bin/activate
+            make builddeb-nosign