Comment #: i-52, clarifications sought about the error domain

issue #53
Change: "The error_domain.json is an optional domain that further describes a bioinformatics workflow"

To: "The error_domain.json is an optional domain to further describe empirical and algorithmic sources and measures of error for a bioinformatics workflow"

- error_domain is no longer **required** in biocompute.json.

biocomputeobject.json

@@ -12,8 +12,7 @@
         "usability_domain",
         "description_domain",
         "execution_domain",
-        "io_domain",
-        "error_domain"
+        "io_domain"
     ],
     "definitions": {
         "bco_id": {