Release tagged versions to PyPI and now alias

When a new tagged version is pushed, this should:

* bdist_wheel it and release to https://pypi.python.org/pypi/datasette
* Set an alias of v0-22-1.datasette.io for the deployed demo

.travis.yml

@@ -24,3 +24,21 @@ jobs:
         - echo "{\"name\":\"datasette-latest-$ALIAS\",\"alias\":\"$ALIAS.datasette.io\"}" > now.json
         - now alias --token=$NOW_TOKEN
       on: master
+    - stage: release tagged version
+      if: tag IS present
+      python: 3.6
+      script:
+        - npm install -g now
+        - export ALIAS=`echo $TRAVIS_COMMIT | cut -c 1-7`
+        - export TAG=`echo $TRAVIS_TAG | sed 's/\./-/g' | sed 's/.*/v&/'`
+        - echo "{\"name\":\"datasette-latest-$ALIAS\",\"alias\":\"$TAG.datasette.io\"}" > now.json
+        - now alias --token=$NOW_TOKEN
+      deploy:
+        - provider: pypi
+          user: simonw
+          distributions: bdist_wheel
+          password:
+            secure: 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
+          on:
+            branch: master
+            tags: true