Fix COPY INTO syntax

[mzumi]

I got an error that is as follows in v.0.5.1.

Error: java.lang.RuntimeException: net.snowflake.client.jdbc.SnowflakeSQLException: SQLコンパイルエラー：
無効なパラメーター「EMPTY_FIELD_AS_NULL」

EMPTY_FIELD_AS_NULL option has been added in v0.5.1, but it seems that syntax is wrong when you use EMPTY_FIELD_AS_NULL = false option.

SQL below is generated when you make EMPTY_FIELD_AS_NULL false.

COPY INTO
  <table_name> 
FROM 
  <stage_file_name> 
FILE_FORMAT = ( TYPE = CSV FIELD_DELIMITER = '<delimiter>' ) EMPTY_FIELD_AS_NULL = FALSE

But acconding to reference, I think SQL should be fixed as follows:

COPY INTO
  <table_name> 
FROM 
  <stage_file_name> 
FILE_FORMAT = ( TYPE = CSV FIELD_DELIMITER = '<delimiter>' EMPTY_FIELD_AS_NULL = FALSE ) 

[u110]

thx!
LGTM!