modularize and add `logicUserAction.js`, `logicBetaJoin.js`, and `logicAlphaStart.js`
reorder functions within .findUserGame()
logicUserAction.js modularization
Merge pull request #344 from tongxiang/refactor-useraction

1) add `logicUserAction.js`, `logicBetaJoin.js`, and `logicAlphaStart.js`, 2) Refactor logicUserAction.js