Update gem specifications

Author: lmrodriguezr

.gitignore

@@ -1,6 +1,7 @@
 *.swp
 *.gem
 *.rbc
+/Gemfile.lock
 /.config
 /coverage/
 /InstalledFiles

Gemfile

@@ -0,0 +1,8 @@
+source 'https://rubygems.org'
+gemspec
+
+group :test do
+  gem 'simplecov'
+end
+
+gem 'rake', '~> 13.0'

Rakefile

@@ -0,0 +1,17 @@
+require 'bundler/gem_tasks'
+require 'rake/testtask'
+
+$:.unshift File.join(File.dirname(__FILE__), 'lib')
+
+require 'gfa/version'
+
+SOURCES = FileList['lib/**/*.rb']
+
+desc 'Default Task'
+task :default => :test
+
+Rake::TestTask.new do |t|
+  t.libs << 'test'
+  t.pattern = 'test/*_test.rb'
+  t.verbose = true
+end