This commit removes the iBatis based ItemReaders and ItemWriter. They
were depricated in the 3.0 line in favor of the MyBatis natively
provided ItemReader and ItemWriter implementations. This removes those
depricated components.
Resolves BATCH-2591
* Moved batch-principles-guidelines to reference guide
* Moved batch-processing-strategies to reference guide
* Moved transactions to reference guide
* Moved spring batch samples notes to a README.md for the samples module