Rename hostname to host.name fields to be consistent

[ruflin]

destination.hostname, device.hostname and source.hostname were renamed to *.host.name to be consitent with the host object.

Related to #62

[webmat]

LGTM

[ruflin]

@webmat If ok for, best squash directly.

[MikePaquette]

@ruflin I think "hostname" is a better ECS name for this field, as we are looking to populate this with the internet hostname which is commonly known as "hostname." See wikipedia hostname.

This too would preserve a consistent use of "hostname" in source.hostname, destination.hostname, and device.hostname. But for consistency, this also means that we would have host.hostname, which has been criticized previously as being redundant, and could seem to run afoul of our Avoid Repetition naming guideline . Nonetheless, since "hostname" is the actual name of the entity stored in the field, I think this justifies keeping it.

Also, in case we decide to keep host.* as a top-level namespace/object/prefix only, the use of "hostname" keeps us clear of conflicts.

Finally, this also allows us to continue to have only one dot in our commonly used "ECS-compatible" fields, an original ECS goal to assist with ease-of-recall and predictability.

I vote for no further changes from *.hostname to *.host.name and for reverting host.name to host.hostname for consistency.

[ruflin]

Renaming host.name to host.hostname is an other way we could go. My current preference is still with host.name but it ties into the discussion here: #71 It would mean hostname is a reusable field.

[webmat]

Yeah I think I'm also in favor of sticking with the widely used naming, in cases like this.

[webmat]

As discussed, we're closing this and we'll be sticking with hostname instead.

[ruflin]

Would be good to add here a comment with reasoning so if we get back to it we know why.