Initial Bitbucket Pipelines configuration

bitbucket-pipelines.yml

+image: openpyxl/openpyxl-ci
+
+pipelines:
+  default:
+  - step:
+      caches:
+        - pip
+      script:
+        - /tools/clean-launch.sh tox --skip-missing-interpreters -- -qrf
+        - export GIT_ID=$(hg tip --template '{node}\n')
+        - export GIT_AUTHOR_NAME=$(hg tip --template '{author|person}\n')
+        - export GIT_AUTHOR_EMAIL=$(hg tip --template '{author|email}\n')
+        - export GIT_COMMITTER_NAME=$(hg tip --template '{author|person}\n')
+        - export GIT_COMMITTER_EMAIL=$(hg tip --template '{author|email}\n')
+        - export GIT_MESSAGE=$(hg tip --template '{desc}\n')
+        - export GIT_BRANCH=$(hg branch)
+        - export GIT_URL=https://bitbucket.org/openpyxl/et_xmlfile
+        - /tools/clean-launch.sh tox -e cov
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