switched check to correct list in AbstractAttributableTO

git-svn-id: https://svn.apache.org/repos/asf/syncope/branches/1_1_X@1601643 13f79535-47bb-0310-9956-ffa450edef68
[SYNCOPE-501] improved management of user virtual attributes, implemented update of the only virtual attributes

git-svn-id: https://svn.apache.org/repos/asf/syncope/branches/1_1_X@1602076 13f79535-47bb-0310-9956-ffa450edef68
[SYNCOPE-501] merge from branch 1_1_X

git-svn-id: https://svn.apache.org/repos/asf/syncope/trunk@1602829 13f79535-47bb-0310-9956-ffa450edef68