add .ruby-gemset

this file will save the gems to project specific location and won’t
require to run bundle install each time I switch to another project.
[#4] PR comments solved
Merge branch 'feature/4_post_page' into feature/5_users_login
[#5] PR comment solved
Merge branch 'feature/5_users_login' into feature/6_blog_post_comments

Conflicts:
	app/controllers/landing_controller.rb