Avoid "It can: Access your data on all websites" warning on installation from Chrome Web Store

[floehopper]

We assume this is due to these permissions which we added to make it easier to host the rules.json file anywhere.

[robd]

I was wondering if this project really needs to be a chrome extension or whether a bookmarklet would be good enough. I'll probably have a crack at hacking together a bookmarklet to work from the same rules file at some point.

[floehopper]

@robd Funnily enough the project started life as a bookmarklet (see commits prior to d420d16). It probably doesn't need to be a Chrome extension, but it was an interesting exercise nonetheless.

We've just had our attention drawn to the "Guess bank transaction explanations" checkbox (see Upload bank transactions - "Guessing transactions" section) when uploading bank statements to FreeAgent which might do some/all of what this Chrome extension does.