JBERET-79 Implement OOXML ExcelStreamingItemReader with StAX; and add tests to ExcelReaderTest for streaming reading.
add tests to read very large xlsx file (over 1 million rows) with ExcelStreamingItemReader;
add tests to read rows with blank cells;
modify ExcelStreamingItemReader to handle inlineStr cell value (as opposed to shared strings table).
Test clean up to run tests in a known order as a temporary fix. Changed to use a DB and files located in the target dir for easy clean-up.