Remove localize formatting rules

[yukihariguchi]

Since Formatting#localize_formatting_rules prevent from overwriting rules, this patch is going to propose to remove Formatting#localize_formatting_rules.

First of all, this method was introduced at #101. But it doesn't make sense to me and unexpected behavior. Not only '円' but also '圓'(it's more formal) or even 'yen' can be used.

[coveralls]

Coverage decreased (-0.003%) to 99.376% when pulling c20176c on yukihariguchi:remove_localize_formatting_rules into 5630a70 on RubyMoney:master.

[antstorm]

@yukihariguchi thanks for the PR, looks legit from what I can tell. Do you have any examples of this? Wiki or any other resource?

Also, CHANGELOG and AUTHORS is updated when releasing a new version, so can you please drop that last commit?

[antstorm]

@yukihariguchi any chance you can rebase this PR and answer my question? Thanks!

[antstorm]

@pwim do you have any suggestions here?

[pwim]

I've taken a look at some of the top ecommerce sites in Japan.

Site	Symbol
http://www.amazon.co.jp/	¥
https://www.yodobashi.com/	¥
https://www.rakuten.co.jp/	円
http://zozo.jp/	¥
https://www.bellemaison.jp/	¥
http://kakaku.com/	¥
https://auctions.yahoo.co.jp/	円
https://www.mercari.com/jp/	¥
https://www.uniqlo.com/jp/	¥

So as of 2018, it seems that using ¥ rather than 円 is more common. Maybe the situation was different back in 2011 when I first made #101, or maybe I was misguided and it wasn't necessary.

Given this, I'm fine for my application displaying "¥500" instead of "500円", and so I'm not opposed to this PR.

This is a breaking change, so it should probably go into the next major version.

[pwim]

Additionally, I'd call out that this changes how Japanese yen is formatted explicitly in the changelog. Something like

Format Japanese Yen the same across all locales. Previously, when I18n.locale == :ja, JPY would be displayed using 円 (e.g. "500円"), whereas in other locales it was displayed as using ¥ (e.g. "¥500"). Now it is always displayed using ¥, even when the locale is set to ja.

[antstorm]

@pwim since I'm not familiar with the matter I trust your judgment. Thank you for pointing out that it's a breaking change and sketching a text for changelog, really appreciate that!

@yukihariguchi can you please rebase the PR?