Fixed messages and comments for UserGroupErrors

ref #39

src/errors/UserGroupErrors.ts

@@ -2,14 +2,14 @@ import { IsString } from 'class-validator';
 import { NotAcceptableError, NotFoundError } from 'routing-controllers';
 
 /**
- * Error to throw when no groupname is set
+ * Error to throw when no groupname is set.
  */
 export class GroupNameNeededError extends NotFoundError {
 	@IsString()
 	name = "GroupNameNeededError"
 
 	@IsString()
-	message = "no groupname is set!"
+	message = "No name is set for this group!"
 }
 
 /**
@@ -32,5 +32,5 @@ export class UserGroupIdsNotMatchingError extends NotAcceptableError {
 	name = "UserGroupIdsNotMatchingError"
 
 	@IsString()
-	message = "The id's don't match!! \n If you wanted to change a usergroup's id: This isn't allowed"
+	message = "The ids don't match!! \n If you wanted to change a usergroup's id: This isn't allowed!"
 }