Add license and platform to the gemspec

This commit adds the MIT license and platform to the gemspec.  The missing license added due to a warning when building the gem.  The platform was added on a whim by noticing it was missing.
Add MIT License to the repository
Add year and copyright holder to the MIT License
Removed MIT-License
Added LICENSE

This commit adds a LICENSE file containing our license info.  This
commit is in response to removing the former file MIT-LICENSE.
Merge pull request #5 from sqm/25534-add-the-mit-license-to-the-has_breadcrumb-gem

#25534 - Add license and platform to the gemspec