Can't resolve Gemfile.lock merge error - ruby-on-rails-4

Question

I tried to run bundle install and this happens, and I can't see to fix it. I don't think there are any merge conflicts in my gem file that I haven't fixed.. but I still can't get rid of this error. How can I do so?
Your Gemfile.lock contains merge conflicts.
Run git checkout HEAD -- Gemfile.lock first to get a clean lock.
this is my gem file:
source 'https://rubygems.org'
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.0.8'
group :test, :development do
gem 'rspec-rails'
end
group :test do
gem 'capybara'
#gem 'selenium-webdriver'
end
# Use sqlite3 as the database for Active Record
group(:development, :test) do
gem 'sqlite3'
end
group :production do
gem 'pg'
gem 'rails_12factor'
end
# Use SCSS for stylesheets
gem 'sass-rails', '~> 4.0.2'
# add bootstrap gem
gem 'bootstrap-sass'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '~> 4.0.0'
# See https://github.com/sstephenson/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', '~> 1.2'
group :doc do
# bundle exec rake doc:rails generates the API under doc/api.
gem 'sdoc', require: false
end
# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'
# Use unicorn as the app server
# gem 'unicorn'
# Use Capistrano for deployment
# gem 'capistrano', group: :development
# Use debugger
# gem 'debugger', group: [:development, :test]
gem 'rubyzip', '0.9.9'

Answer 1

It's actually very straightforward. Here is an article that explains the difference between the gemfile and the gemfile.lock. (You can edit Gemfile.lock to get rid of the conflicts manually)
http://rubyinrails.com/2013/12/what-is-gemfile-lock/