Merge branch 'release/0.3.0' into develop
gem update.
add links in the top bar.
add gritter gem.
add and fix some styles.
remove old comment.
refactor: add partial for error explanations.
Gem update and install Gritter.
Slightly edit some js files.
Edit logged/unlogged top_bar
Disable turbolinks, add gritter, log a timestamp.
Add a message (wip).
Add the JS tag.

This solves the Gritter problem.
add a gitkeep file
custom session controller
add a custom route for sessions
remove a test message
add admin user in seeds.rb
move version number constant.

moved DnsJournal::Application::VERSION from domains controller to application.rb
version bump: 0.3.1