Log Message:
math/ruby-roo: update to 2.8.2

##  [2.8.2] 2019-02-01
### Changed/Added
- Support range cell for Excelx's links [490](https://github.com/roo-rb/roo/pull/490)
- Skip `extract_hyperlinks` if not required \ 
[488](https://github.com/roo-rb/roo/pull/488)

### Fixed
- Fixed error for invalid link [492](https://github.com/roo-rb/roo/pull/492)

##  [2.8.1] 2019-01-21
### Fixed
- Fixed error if excelx's cell have empty children \ 
[487](https://github.com/roo-rb/roo/pull/487)