Add instruction to refresh ~/.bashrc after RAILS_ENV

I ran into a problem after setting up my RAILS_ENV in step 10. Using the command `source ~/.bashrc` after updating it fixed it on Ubuntu for me.

```
deploy@exchange:~/peatio/current$ bundle exec rake db:setup
rake aborted!
uninitialized constant MailsViewer
/home/deploy/peatio/current/config/routes.rb:14:in `block in <top (required)>'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/actionpack-4.0.2/lib/action_dispatch/routing/route_set.rb:341:in `instance_exec'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/actionpack-4.0.2/lib/action_dispatch/routing/route_set.rb:341:in `eval_block'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/actionpack-4.0.2/lib/action_dispatch/routing/route_set.rb:319:in `draw'
/home/deploy/peatio/current/config/routes.rb:9:in `<top (required)>'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application/routes_reloader.rb:40:in `each'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application/routes_reloader.rb:40:in `load_paths'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application/routes_reloader.rb:16:in `reload!'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application/routes_reloader.rb:26:in `block in updater'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/activesupport-4.0.2/lib/active_support/file_update_checker.rb:75:in `call'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/activesupport-4.0.2/lib/active_support/file_update_checker.rb:75:in `execute'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application/routes_reloader.rb:27:in `updater'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application/routes_reloader.rb:6:in `execute_if_updated'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application/finisher.rb:69:in `block in <module:Finisher>'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/initializable.rb:30:in `instance_exec'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/initializable.rb:30:in `run'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/initializable.rb:55:in `block in run_initializers'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/initializable.rb:54:in `run_initializers'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application.rb:215:in `initialize!'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/railtie/configurable.rb:30:in `method_missing'
/home/deploy/peatio/current/config/environment.rb:5:in `<top (required)>'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application.rb:189:in `require_environment!'
/home/deploy/peatio/current/vendor/bundle/ruby/2.1.0/gems/railties-4.0.2/lib/rails/application.rb:250:in `block in run_tasks_blocks'
Tasks: TOP => db:setup => db:schema:load_if_ruby => environment
(See full trace by running task with --trace)
```