Allow for empty strings in create-blob API call

Author: mikedeboer

api/v3.0.0/routes.json

@@ -529,6 +529,7 @@
                 "content": {
                     "type": "String",
                     "required": true,
+                    "allow-empty": true,
                     "validation": "",
                     "invalidmsg": "",
                     "description": ""

index.js

@@ -259,7 +259,7 @@ var Client = module.exports = function(config) {
                 if (typeof value != "boolean" && !value) {
                     // we don't need to validation for undefined parameter values
                     // that are not required.
-                    if (!def.required)
+                    if (!def.required || (def["allow-empty"] && value === ""))
                         continue;
                     throw new error.BadRequest("Empty value for parameter '" +
                         paramName + "': " + value);