Add npm prepare script (#2)

- Support consuming package directly from GitHub by adding npm prepare script.

Author: mdmower-csnw

package.json

@@ -21,6 +21,7 @@
     "tdd": "concurrently -r -p '' -k 'npm run watch' 'npm run watch:test'",
     "test": "npm run pre-test && ava --timeout=300s --verbose",
     "stresstest": "seq 1 10 | xargs -I{} npm test",
+    "prepare": "npm run clean && npm run build:server",
     "prepublishOnly": "npm test",
     "pre-test": "npm run clean && npm run format-check && npm run build:server",
     "watch": "tsc -w",