use "data-tiddlyfox-path", not currentlocation

[skierpage]

Fixes #47 for me when I change the path in the developer console, but I didn't rebuild or retest the whole extension.

[buggyj]

I am unsure if this addon will work correctly with the proposed change.

The existing mechanism has be extensively tested with various path names and multiple current saving of twc and tw5 - a lot of testing (and therefore a lot of effort) would be need before I would consider this pull request.