filterelement: Check that invalid filters cannot be set
filterelement: Check that invalid filters cannot be set

Change-Id: Idb82baf7177fb62c750023d732bbbb742f7c6939

ESTOS/kms-core,Kurento/kms-core,ESTOS/kms-core,ESTOS/kms-core,Kurento/kms-core,Kurento/kms-core,ESTOS/kms-core,Kurento/kms-core