Bundler could not find compatible versions for gem “spree_core"

I’m trying to install spree_braintree gem to integrate braintree gateway with spree 3.0.1. When I run “bundle install”, I get this error “Bundler could not find compatible versions for gem “spree_core”". This is my Gemfile.

source 'https://rubygems.org'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.2.1'
# Use sqlite3 as the database for Active Record
gem 'sqlite3'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '~> 4.1.0'
# See https://github.com/rails/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby

# Use jquery as the JavaScript library
gem 'jquery-rails'
# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.0'
# bundle exec rake doc:rails generates the API under doc/api.
gem 'sdoc', '~> 0.4.0', group: :doc

# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'

# Use Unicorn as the app server
# gem 'unicorn'

# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug'

  # Access an IRB console on exception pages or by using <%= console %> in views
  gem 'web-console', '~> 2.0'

  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
end

gem 'spree', '3.0.1'
gem 'spree_gateway', github: 'spree/spree_gateway', branch: '3-0-stable'
gem 'spree_auth_devise', github: 'spree/spree_auth_devise', branch: '3-0-stable'
gem 'spree_braintree', :git => 'git://github.com/rortechie/spree-braintree.git'

Error:

Bundler could not find compatible versions for gem "spree_core":
  In snapshot (Gemfile.lock):
    spree_core (3.0.1)

  In Gemfile:
    spree_braintree (>= 0) ruby depends on
      spree_core (~> 1.0.0) ruby

Running `bundle update` will rebuild your snapshot from scratch, using only
the gems in your Gemfile, which may resolve the conflict.

I also tried removing Gemfile.lock and run bundle install but it didn't help.

rortechie / spree-braintree

Bundler could not find compatible versions for gem “spree_core" #1