Add more tests
Update README.md
Change class name from AllTests to WorkbookAccessorTests
Upgrade dependecies
Bump verison to v1.2.0-SNAPSHOT
Fix JavaDoc
Add WorkbookWriter#setSheetName, WorkbookReader#withHeader &
WorkbookReader#withoutHeader
Add toMultimap and override basic methos
Correct Number writing behavior
Delete testing file
Ready to release v1.2.0
Delete testing output file