Validate things interaction forms in TM

[farshidtz]

The forms of the things interaction may be wrong. Some uri variables are not used. The second form is redundant since every uri variable is optional:

wot-discovery/implementations/example-directory-oauth2.td.json

Lines 99 to 132 in f03fa88

	"forms": [
	{
	"href": "/things",
	"htv:methodName": "GET",
	"response": {
	"description": "Success response",
	"htv:statusCodeValue": 200,
	"contentType": "application/ld+json"
	},
	"scopes": "readAll"
	},
	{
	"href": "/things{?offset,limit,sort_by,sort_order}",
	"htv:methodName": "GET",
	"response": {
	"description": "Success response",
	"htv:statusCodeValue": 200,
	"contentType": "application/ld+json",
	"htv:headers": [
	{
	"htv:fieldName": "Link"
	}
	]
	},
	"additionalResponses": [
	{
	"description": "Invalid query arguments",
	"contentType": "application/problem+json",
	"htv:statusCodeValue": 400
	}
	],
	"scopes": "readAll"
	}
	]

Related comment: #273 (comment)_
Also related to #86