Email users on document create for a schema when specified

[alexgao1]

• Create an option in a schema's definition.json to allow for emailing of a certain set of users whenever a document of that particular schema type is created
• emailOnCreate should be its name, it should accept boolean values, and should default to false if omitted in the definition.json file
• It should email the user that created the document, any users with the _vetter role, and all administrators (users with the _administrator plus the global administrator(s))
• It should log that it won't be doing anything if there is no mail server when it is enabled/set to true