Add Dutch 'Secure your wallet' page

[Dr-Nix]

This implements the new extensive secure-your-wallet page in Dutch.

Also a strange English sentence is corrected.

[saivann]

@whenlit : Is it possible for your to review this? This page is sensitive, and we should be sure that it's 100% accurate and has the same meaning then the english page.

@Dr-Nix : Concerning the english sentence, perhaps we could just use "to transfer value easier than ever"? I think that your suggestion is just a bit too long and ends-up on 5 lines.

[saivann]

BTW, I am working to make it possible to translate bitcoin.org with transifex in the future.

[Dr-Nix]

@whenlit Yes a review would be welcome of course.
@saivann Transifex would be great, but then I suppose it would be a combination of transifex and github? I mean, the structure of the site needs to be adapted as well (I mean files like _config.yml)
Regarding the sentence: I don't care as long as it is correct English.

[saivann]

@Dr-Nix : Yes, I would update the README to explain how to integrate translations for transifex. That would seperate "translators" and "integrators". Thus giving us more help with translations from non technical people.

[saivann]

This update has been included in the transifex branch which has been merged today. Thanks!