improve readme.
move MyConnect.scala to package db.
rename folder 'model' to 'models'.
move test class DatabaseTest, QueryTest to test/scala/db.
remove unused file.
add package db to header of file test.add package db to header of file
test.add package db to header of file test.add package db to header of
file test.add package db to header of file test.add package db to header
of file test.add package db to header of file test.add package db to
header of file test.