Merge pull request #24 from gocardless/drop-ruby-2.0-support

Drop support for unsupported Rubies 2.0 and 2.1, add 2.4

Author: nickcampbell18

.ruby-version

@@ -1 +1 @@
-2.0.0-p353
+2.4.1

.travis.yml

@@ -1,10 +1,9 @@
 language: ruby
 
 rvm:
+  - 2.4.1
   - 2.3.4
   - 2.2.6
-  - 2.1.10
-  - 2.0.0-p648
 
 addons:
   postgresql: "9.3"
@@ -23,14 +22,3 @@ env:
     - "ACTIVERECORD_VERSION=4.2.9"
     - "ACTIVERECORD_VERSION=5.0.5"
     - "ACTIVERECORD_VERSION=5.1.3"
-
-matrix:
-  exclude:
-    - rvm: 2.1.10
-      env: "ACTIVERECORD_VERSION=5.0.5"
-    - rvm: 2.0.0-p648
-      env: "ACTIVERECORD_VERSION=5.0.5"
-    - rvm: 2.1.10
-      env: "ACTIVERECORD_VERSION=5.1.3"
-    - rvm: 2.0.0-p648
-      env: "ACTIVERECORD_VERSION=5.1.3"

activerecord-safer_migrations.gemspec

@@ -12,6 +12,8 @@ Gem::Specification.new do |gem|
   gem.homepage      = "https://github.com/gocardless/activerecord-safer_migrations"
   gem.license       = "MIT"
 
+  gem.required_ruby_version = "~> 2.2"
+
   gem.add_runtime_dependency "activerecord", ">= 4.0"
 
   gem.add_development_dependency "pg", "~> 0.21.0"