Enhancement/teradata lastrowid (#363)

* Initial change to remove ESCAPE from teradata syntax

* Revert "Initial change to remove ESCAPE from teradata syntax"

This reverts commit 81489e9.

* Fix lastrowid error for Teradata adapter

* further update to teradata adapter

pydal/adapters/teradata.py

@@ -19,3 +19,10 @@ def close(self):
         # leading to SQL_ACTIVE_STATEMENTS limit errors
         self.cursor.close()
         super(Teradata, self).close()
+
+    def lastrowid(self, table):
+        # Teradata cannot retrieve the lastrowid for an IDENTITY Column
+        # and they are not sequential anyway.  
+        # Similar to the NullCursor class, return 1
+        return 1
+