Changing the Payload Bindings to Content Type Bindings

[egekorkan]

After talking with @mjkoster , we have realized that payload binding wording might be confusing since it sometimes goes into what the platform dictates and goes out of the form. A proposal would be to change it to Content Type Bindings.

[egekorkan]

Call of 15.03:

• @mmccool prefers payload binding
• @sebastiankb : if the data schema with hue or ocf goes in platforms, this change makes sense
• @lu-zero : it should be possible to map from contentType term to the supported serializers
• We should be clear about our expectations on when something becomes a payload/content type binding
• The group tends towards content type binding
• Alternative would be to just say content binding.

[egekorkan]

From the discussion at #226, it seems that we can drop the distinction and avoid the naming problem.

[egekorkan]

Also see #281