Further es_ES grammar corrections

[samuelpx]

Summary

Upon working on the pt_BR version I found some grammar issues with the es_ES version after some tests.

Thousand correction

While spanish follows regular conventions for thousands (i.e. "two thousand" is simply directly translated) when there is only "one thousand", the "one" in spanish is ommited.

Currently "one thousand" gets transcribed in spanish as "Uno mil", it should just be "mil"

Five-hundred correction

Five hundred (500) currently is transcribed as "cinccientos", it is an irregular numeral, so it does not follow the prefix rules, so "five hundred" is actually "quinhentos" in spanish.

Euro nomenclature for cents

While dollar cents are translated as "centavos" correctly, euro cents are actually more commonly referred to as "céntimo" (singular, with "céntimos" being the plural).

Sorry for not noticing these items while submitting the last issue, thank you for your attention!