Changed the logic for showPreliminary

Should be simpler now and no longer rely on dataVersion
Merge pull request #542 from SpiderOak/fix-for-showPreliminary-logic

Changed the logic for showPreliminary

I've confirmed that:
* Prelim screen doesn't show on fresh Blue install, or update
* Prelim screen does show on Orange when:
  * starting a virgin install
  * subsequent restarts of the app so long as the "Login" button wasn't hit
    * even if other, explanatory links were followed
  * update if the prelim screen was not yet inhibited
 * Prelim screen does *not* show in Orange after the Login button was hit
  * even on subsequent app restarts
   * even after app updates