Rename haml-lint gem to haml_lint

In order to properly follow RubyGems conventions for naming gems, rename
the gem from having a dash to an underscore.

CHANGELOG.md

@@ -1,5 +1,10 @@
 # HAML-Lint Changelog
 
+## master (unreleased)
+
+* Rename `haml-lint` gem to `haml_lint` to follow RubyGems [conventions for
+  naming gems](http://guides.rubygems.org/name-your-gem/)
+
 ## 0.12.0
 
 * Fix non-visible line number on light-colored terminal backgrounds

README.md

@@ -1,6 +1,6 @@
 # HAML-Lint
 
-[![Gem Version](https://badge.fury.io/rb/haml-lint.svg)](http://badge.fury.io/rb/haml-lint)
+[![Gem Version](https://badge.fury.io/rb/haml_lint.svg)](http://badge.fury.io/rb/haml_lint)
 [![Build Status](https://travis-ci.org/brigade/haml-lint.svg)](https://travis-ci.org/brigade/haml-lint)
 [![Code Climate](https://codeclimate.com/github/brigade/haml-lint.png)](https://codeclimate.com/github/brigade/haml-lint)
 [![Inline docs](http://inch-ci.org/github/brigade/haml-lint.svg?branch=master)](http://inch-ci.org/github/brigade/haml-lint)
@@ -35,7 +35,7 @@ your [SCM hooks](https://github.com/brigade/overcommit).
 ## Installation
 
 ```bash
-gem install haml-lint
+gem install haml_lint
 ```
 
 ## Usage

haml-lint.gemspec → haml_lint.gemspec

@@ -3,7 +3,7 @@ require 'haml_lint/constants'
 require 'haml_lint/version'
 
 Gem::Specification.new do |s|
-  s.name             = 'haml-lint'
+  s.name             = 'haml_lint'
   s.version          = HamlLint::VERSION
   s.license          = 'MIT'
   s.summary          = 'HAML lint tool'