Fix relations between projects and users
Avoid session to be destroyed when cache is cleared
Print user's username
Add project name and role of the user in the navbar

close #14
Add link to the project backlog in the scrumbar
Revert a change in navbar
Add scrumbar in backlog page
Rename ProjectUser to Membership
Add list of members on project page

reference #13
Add link to project page in the navbar
Rename variable