Upgrade libraries
Merge pull request #33 from rintcius/upgrades

Upgrade libraries
Add dataFormat to CellStyle; add StyledCell; add style to Cell; add Workbook.styled
Merge pull request #34 from rintcius/styles

Various style additions
Update versions.
Downgrading to 2.11.2 because of

https://groups.google.com/forum/#!topic/scala-internals/SSD9BNJaFbU