Merge branch 'remove-gemfile-lock'

When I run automated security checks on a gem
I want the alerts to be mostly relevant
So that no-one gets confused by unnecessary false positives
And I don't get used to ignore warnings

The Gemfile.loclk in a gem is only used during development
(it is not used when the gem is installed in a project),
it is arguably not essential to lock dependencies in development,
and having the file causes automatic security scanners to trigger
most often that not alerts that are not relevant.

Note: Hakiri does also perform code analysis, so I'll keep it.
See https://hakiri.io/github/gonzalo-bulnes/simple_token_authentication/master

CHANGELOG.md

@@ -3,6 +3,12 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
+## [Unreleased] - 2017-12-21
+
+## Fixed
+
+- Removed the `Gemfile.lock` - mostly to acknowledge that it was used only in development and is not really needed.
+
 ## [1.15.1] - 2017-01-26
 
 ## Fixed
@@ -268,6 +274,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This [gist][gist] did refactor the Jose Valim's code into an `ActiveSupport::Concern`.
 
 [gist]: https://gist.github.com/gonzalo-bulnes/7659739
+[Unreleased]: https://github.com/gonzalo-bulnes/simple_token_authentication/compare/v1.15.1...master
 [1.15.1]: https://github.com/gonzalo-bulnes/simple_token_authentication/compare/v1.15.0...v1.15.1
 [1.15.0]: https://github.com/gonzalo-bulnes/simple_token_authentication/compare/v1.14.0...v1.15.0
 [1.14.0]: https://github.com/gonzalo-bulnes/simple_token_authentication/compare/v1.13.0...v1.14.0