Automated install steps + new IndexedDB plugin

[JamesMessinger]

Hi @DickvdBrink and @Nimrodxx. Thanks again for open-sourcing this plug-in. I've created a new IndexedDB plugin that uses this plugin instead of the MSOpenTech one. I also made a few changes to this plugin to simplify the installation process. Here are the changes I made:

1. Added an after_plugin_install hook that takes care of modifying the .jsproj and .sln files, so now there aren't any manual post-installation steps
2. Updated the ReadMe file to get rid of the manual installation steps, included the Cordova CLI installation command, and linked to the async IndexedDB plugin
3. Cordova is moving all plugins to npm, so I added a package.json file and renamed the plugin according to the new naming convention (cordova-plugin-websql-async). You can publish the plugin to npm using the npm publish command. Let me know once you've done that, and I'll update the IndexedDB plugin to point to your npm package.

[JamesMessinger]

Just committed some more fixes.

1. Fixed a global variable leak (idxRow)
2. Added logic to prevent duplicate SQLite references when updating the plugin/platform
3. Fixed a bug where clearQueue() was sometimes being called on the wrong object

[DickvdBrink]

Thanks! Will look at this tomorrow :) Nice fixes btw :)!

[JamesMessinger]

With these fixes in place, almost all of the IndexedDBShim unit tests pass on Windows Phone 8.1. Only 19 tests (out of 314) are still failing. All of the failing tests are caused by these three bugs:

• No errors on primary key constraint violations No error is being thrown when two records are added with the same primary key. So, effectively, IDBObjectStore.add() is behaving like IDBObjectStore.put().
• Duplicate primary keys in simultaneous transactions If a table has autoIncrement keys, and two different transactions simultaneously add data to the table, then both new records get the same generated key.
• Some errors are being suppressed This catch block in Database.js was suppressing errors entirely. I fixed that by adding a call to onError(). Now errors are being thrown appropriately, but they're being caught by Cordova, which then fires a cordovacallbackerror event. That's better than nothing, since this event can be listened for, but it's supposed to fire a window.onerror event instead.

[DickvdBrink]

@BigstickCarpet, merged by @Nimrodxx and thanks for the PR.

Need to look into the Duplicate primary keys in simultaneous transactions as I find that the most dangerous issue. Thanks for testing!

[JamesMessinger]

agreed, that seems like the top priority