Update dutch translation Iota wallet.

Created by: eddits

Hello Iota people, I saw a few misspelled dutch words in the wallet, so I mentioned on the "dev's" slack channel. And someone said I could check it myself and gave me the file. So I changed the words and found a few other misspelled words and some capitals in the wrong place. Of course I left the English words which are so common these days in our language untouched. I can help out with other stuff which involves the dutch language or here in the Netherlands, don't hesitate to ask me.