chore(project): build distribution before bumping the version

This ensures we build (and test) the to-be-published thing before
we tag the tool.

This also ensures that the actual npm publish step is a as simple
as possible activity, which it should be.

package.json

@@ -9,7 +9,7 @@
     "test": "karma start test/config/karma.unit.js",
     "distro": "node tasks/build-distro.js",
     "test:distro": "node tasks/test-distro.js",
-    "prepublishOnly": "run-s distro test:distro"
+    "preversion": "run-s distro test:distro"
   },
   "repository": {
     "type": "git",