new-quiz buttons live in table
common links and "Logout" => table
print username near Logout button
views/welcome: note that file can be removed
guest login
prep-quizs: exchange 'right' and 'all'

let it look like right / all.
prep-quizs: bgcolor only two last columns (score)
preps can filter quizes by user
prep-quizs: add h1 with description of quizes set
model quiz: index 'user', 'created_at' and 'state'
swith all-tasks, one-task
quiz bgcolor: right is green, my is yellow
more tasks in quiz hello
fix ambigous tests

the number should not contain zeros in decimal notation