Upgrade to Circle 2 (mattloper#4)

CircleCI 1.0 is being retired next month.

.circleci/config.yml

@@ -0,0 +1,37 @@
+version: 2
+jobs:
+  build:
+    docker:
+      - image: circleci/python:2
+
+    working_directory: ~/repo
+
+    steps:
+      - checkout
+
+      - run:
+          name: Install container dependencies
+          command: |
+            sudo apt-get update
+            sudo apt-get install -qq gfortran liblapack-dev
+
+      - run:
+          name: Install python dependencies
+          command: |
+            mkdir -p venv
+            virtualenv venv
+            . venv/bin/activate
+            # Hack to disable the progress bar
+            set -o pipefail; pip install -r requirements.txt | cat
+
+      - run:
+          name: Show versions
+          command: |
+            . venv/bin/activate
+            pip freeze
+
+      - run:
+          name: Run tests
+          command: |
+            . venv/bin/activate
+            make test