feat #805 change `rootFolderPath` in NodeJS

This commit changes the `Aria.rootFolderPath` to point to the project's folder (i.e. the one containing `node_modules`) instead of the AT installation folder, when the framework is loaded from NodeJS using `require('ariatemplates')`.

It doesn't make much sense to point to a folder inside `node_modules/ariatemplates` as a root path, since we won't expect the user to create any files manually there. Hence it's enough to create the `aria.*` entry in the URL map, instead of altering `rootFoldePath`. 

Note that this commit is backward-incompatible if someone used sth like this intheir NodeJS code:

    folder = Aria.rootFolderPath + "../../../"

i.e. any relative reference using the `rootFolderPath`.

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The main added value here is that if the user can easily change the `rootFolderPath` without worrying of doing harm to AT core files (no need to update the root map additionally).

As I noted in the commit message, this change is backward incompatible, on the other hand it can be treated as a bugfix :) Any opinions if we should wait for 1.5.1 to include this?