[Tagging] RFC - More sensible values for fountain=*

[Davidoskky]

> why are you sure it is a fountain? And what has it to do with it having a tap? if it isn’t a tap it will not help if it had one.

I'm not sure about anything anymore...

Maybe it is not a fountain, the problem is that I have no idea how that 
could be tagged with the current tagging scheme.

It is currently tagged as natural=spring, which it clearly is not since 
it is not a natural formation and it is way too low altitude to be a 
spring anyway.

> If this is still about laundry sinks, I suggest to not see them as fountains.
No, this is not for laundry; the specific use of this fountain is not 
exactly clear to me but I guess mostly to provide water for cleaning 
houses and watering plants.