Add missed Spanish tranlations

[Chocofede]

Hi,

I've seen that the new blog update is missing some Spanish translations, so, I've added them and homogenized the translation strings, to make it sound Spanish (From Spain).

I will do a Pull Request from my repo to master. Please, let me know if that's Ok or if I have to do it in a different way.

[Chocofede]

I created the #548 pull request for this.

[daftspunk]

Merged. Thanks!