bugfix and set default sql parser

[sunnycamel]

In doc it says db tables is create and migrate by execute the sql scripts in assets directory. In fact in code the db table is create by the utilize the info of annotated model class. SQLiteOpenHelper will set db version after execute the onCreate, this will case the onCreate got the wrong db version, and some migration sql script will never be executed. I correct this by the first commit.

The second commit will set the default sql parser to "delimited". This will support multi-line sql script.