Some big modification today and yesterday in this commit

M: add `grade` and `duration` member variables to .domains.impl.BookInfo
M: modify .data.impl.BookDataRW to adjust to the modified BookInfo class

A: create .commons.OprStatus to store operation status of services
M: modify everything under .service and .service.impl, the return type
of them are changed to "int"

M: modify .service.impl.TransMgmtServiceImpl.bookRenting(String,
String), add a parameter (int duration) to represent the duration of the
renting. add a condition to judge whether the renting is valid (member
remaining account)
M: modify .service.impl.TransMgmtServiceImpl.bookReturning, the
parameter setting of objects of BookInfo and MemberInfo

A: add some private methods in .service.impl.TransMgmtServiceImpl
Signed-off-by: lrcry <lrcry@vip.qq.com>