Fix small typo in usage section

Had twice the word 'be'
Merge pull request #41 from mathieugagne/patch-1

Fix small typo in usage section
Test for a module that does not exist?
Switch to minitest, as rspec is not being used.
Get first working specs of the is_tablet_device?
Add tablet detection for WinRT tablets.
Modify rake to run minitest tests, travisci support.
Consistent quotes.
Support for >= 1.9.3 means we can use require_relative.
Can call the method directly.
No need for minitest in the gemspec.
Refactor.
Move indention back.
Merge pull request #42 from darrencauthon/add_windows_surface_support

Add tests, and windows surface support
Create the tablet file.
Refactor the user agent list to the tablet module.
Move the user agent code to the tablet module.
Use the new tablet check method.
Add mobile detect json.
Rake task to parse the mobile detect data.