Support different schemes for jdbc driver url when creating external jdbc table

CREATE TABLE test_postgres (
 id INT,
 string_col STRING)
PRODUCED BY DATA SOURCE JdbcDataSource(
'{"database.type":"POSTGRES",
"jdbc.url":"jdbc:postgresql://localhost:5432/functional",
"jdbc.driver":"org.postgresql.Driver",
"driver.url":"hdfs://localhost:20500/test-warehouse/data-sources/jdbc-driver/postgresql-jdbc.jar",
"dbcp.username":"hiveuser",
"dbcp.password":"password",
"table":"alltypes"}');