[PATCH] Unique index name for column aggregation key column

When using column aggregation colum with the same name on multiple models, and exporting schema to database, I have a collisions with names in Oracle (I think others are affected too).

{{
CREATE INDEX "type" ON "nt_organism_property" ("type")
CREATE INDEX "type" ON "nt_property" ("type")
CREATE INDEX "type" ON "st_node" ("type")
}}

I propose to prefix the index name with the table name