Clean dist before prepublish

Otherwise you risk accidentally publishing stale files from a previous release.

Author: jfirebaugh

package.json

@@ -84,7 +84,7 @@
     "mocha": "mocha --expose-gc test/runner test/tests --timeout 15000",
     "mochaDebug": "mocha --expose-gc --debug-brk test/runner test/tests --timeout 15000",
     "postinstall": "node lifecycleScripts/postinstall",
-    "prepublish": "npm run babel",
+    "prepublish": "rm -rf dist && npm run babel",
     "rebuild": "node generate && npm run babel && node-gyp configure build",
     "rebuildDebug": "node generate && npm run babel && node-gyp configure --debug build",
     "recompile": "node-gyp configure build",