replace spans used by partials with divs
clip any overflow

* dygraph was doubling the size of the div/canvas (probably for hidpi
* support), so we set overflow: hidden to avoid scrolling the page.
add link back to check group
cleanup
created a proper view model for Check
moved helper method to model
support metrics by display_name()
display full check/metric info
added 'create trigger' button to detail view
wrap each check in a div.row so metrics flow correctly