Group's management.
Providing some faeture from #80.
    + Update details' page with contact and memberships infos.
    + Add Create group (from link only for now)
    + Add Delete group (from link only for now)
    + Add Edit group from details' page.
    + Add membership view based on available requirements.
    + Add membership application link (not bound).
    + Add membership revoking link (not bound).
    + Check group's sponsors & admin privileges.
Use wtform feature to check new password input.
Move some people form field info to optional.
Add release infos.
Update redirection from login page to allow 3rd parties
to redirect to them.
License agreement's management
    Add some feature from #81
    + Create license form from /settings
    + Edit license form from /settings
    + Remove license from direct request url.
    + Enable selection from group edit form.
Add group type's management.
Add Github organization team management from group edition page.
    + User can bind/create their group into project's organization.