Replace page_title with page-title. Correct margin for some blocks/layouts

app/assets/stylesheets/common.scss

app/assets/stylesheets/gitlab_bootstrap/blocks.scss

app/assets/stylesheets/gitlab_bootstrap/typography.scss

app/assets/stylesheets/sections/nav.scss

app/assets/stylesheets/sections/projects.scss

app/assets/stylesheets/sections/votes.scss

app/assets/stylesheets/sections/wiki.scss

app/views/admin/background_jobs/show.html.haml

app/views/admin/groups/edit.html.haml

app/views/admin/groups/index.html.haml

app/views/admin/groups/new.html.haml

app/views/admin/groups/show.html.haml

app/views/admin/projects/index.html.haml

app/views/admin/projects/show.html.haml

app/views/admin/users/edit.html.haml

app/views/admin/users/index.html.haml

app/views/admin/users/new.html.haml

app/views/admin/users/show.html.haml

app/views/dashboard/issues.html.haml

app/views/dashboard/merge_requests.html.haml