Update README.md

Bump "require" version in preparation of the 2.0.0 release

Merge pull request box#67 from box/caching_strategies

Caching strategies

Merge pull request box#60 from Lewiscowles1986/Update-XLSX-Reader

Separated getCellValue into multiple functions

Merge pull request box#48 from box/add_support_for_more_cell_types

Add support for more cell types

Merge pull request box#44 from box/bump_to_v1.0.9

Bump to version 1.0.9

Merge pull request box#37 from box/bump_to_version_1.0.8

Bump to version 1.0.8

Merge pull request box#34 from box/bump_version_to_1.0.7

Bump version to 1.0.7

Merge pull request box#31 from box/bump_version_to_1.0.6

Bump version to 1.0.6

Merge pull request box#25 from box/bump_version_to_1.0.5

Bump version to 1.0.5

Merge pull request box#22 from box/bump_version_to_1.0.4

Bump version to 1.0.4