switch from prepublish to prepare in package.json, also ignore npm 5 lock file

Author: David Frank

.gitignore

@@ -33,3 +33,7 @@ node_modules
 
 # Babel-compiled files
 lib
+
+# Ignore package manager lock files
+package-lock.json
+yarn.lock

package.json

@@ -14,7 +14,7 @@
   },
   "scripts": {
     "build": "cross-env BABEL_ENV=rollup rollup -c",
-    "prepublish": "npm run build",
+    "prepare": "npm run build",
     "test": "cross-env BABEL_ENV=test mocha --compilers js:babel-register test/test.js",
     "report": "cross-env BABEL_ENV=coverage nyc --reporter lcov --reporter text mocha -R spec test/test.js",
     "coverage": "cross-env BABEL_ENV=coverage nyc --reporter json --reporter text mocha -R spec test/test.js && codecov -f coverage/coverage-final.json"