chg: [artifact] Changed the `hashes` attribute into the different hash type attributes

- A change to adopt the same logic as file objects
  regarding the different hash values
- In STIX 2.1 an Artifact object is not necessarily
  linked to a File object and both referenced by
  an Observed Data object. In some cases Artifact
  objects are referenced for instance by Malware
  objects, in which case they describe the actual
  malware sample. It is then usefull to have the
  different hash values in single attributes rather
  than concatenated in a text attribute

objects/artifact/definition.json

@@ -10,11 +10,11 @@
       "misp-attribute": "text",
       "ui-priority": 0
     },
-    "hashes": {
-      "description": "Specifies a dictionary of hashes for the contents of the url or the payload_bin.  This property MUST be present when the url property is present. (should be file with relationships?)",
-      "misp-attribute": "text",
-      "multiple": true,
-      "ui-priority": 0
+    "md5": {
+      "description": "[Insecure] MD5 hash (128 bits)",
+      "misp-attribute": "md5",
+      "recommended": false,
+      "ui-priority": 1
     },
     "mime_type": {
       "description": "Whenever feasible, this value SHOULD be one of the values defined in the Template column in the IANA media type registry [Media Types]. Maintaining a comprehensive universal catalog of all extant file types is obviously not possible. When specifying a MIME Type not included in the IANA registry, implementers should use their best judgement so as to facilitate interoperability.",
@@ -27,8 +27,46 @@
       "misp-attribute": "text",
       "ui-priority": 0
     },
+    "sha1": {
+      "description": "[Insecure] Secure Hash Algorithm 1 (160 bits)",
+      "misp-attribute": "sha1",
+      "recommended": false,
+      "ui-priority": 1
+    },
+    "sha256": {
+      "description": "Secure Hash Algorithm 2 (256 bits)",
+      "misp-attribute": "sha256",
+      "ui-priority": 1
+    },
+    "sha3-256": {
+      "description": "Secure Hash Algorithm 3 (256 bits)",
+      "misp-attribute": "sha3-256",
+      "recommended": false,
+      "ui-priority": 0
+    },
+    "sha3-512": {
+      "description": "Secure Hash Algorithm 3 (512 bits)",
+      "misp-attribute": "sha3-512",
+      "recommended": false,
+      "ui-priority": 0
+    },
+    "sha512": {
+      "description": "Secure Hash Algorithm 2 (512 bits)",
+      "misp-attribute": "sha512",
+      "ui-priority": 1
+    },
+    "ssdeep": {
+      "description": "Fuzzy hash using context triggered piecewise hashes (CTPH)",
+      "misp-attribute": "ssdeep",
+      "ui-priority": 0
+    },
+    "tlsh": {
+      "description": "Fuzzy hash by Trend Micro: Locality Sensitive Hash",
+      "misp-attribute": "tlsh",
+      "ui-priority": 0
+    },
     "url": {
-      "description": "The value of this property MUST be a valid URL that resolves to the unencoded content.",
+      "description": "The value of this property MUST be a valid URL that resolves to the unencoded content. When present, at least one hash value MUST be present too.",
       "misp-attribute": "url",
       "ui-priority": 0
     }
@@ -41,5 +79,5 @@
     "url"
   ],
   "uuid": "0a46df3a-bd9b-472c-a1e7-6aede7094483",
-  "version": 2
-}
+  "version": 3
+}