Fix memory leak and change spki_table_get_all signature

-spki_table_add_entry
	If the entry was allready in the table, the allocated
	memory wasnt freed.

-spki_table_get_all
	The function now returns a array instead of a linked
	list.

-struct spki_record
	Remove next pointer because we dont return linked lists anymore.

-spki_table_remove_entry
	Remove free call -> memory could be on the stack.