Retrieve attributes from the specified table.
optional parameter(only select a row):
Excemple:
GET https://myserver/xcatws/tables/ppc?userName=xxx&password=xxx
Dump all content in ppc table.
GET https://myserver/xcatws/tables/ppc?userName=xxx&password=xxx&col=nodetype&value=lpar&attribute=parent&attribute=hcp
Display the first row satify the condition "nodetype=lpar", only return attribute "parent" and "hcp".