added an edit api for systemnode objects that replaces the previous delete api and has a new put method for editing systemnodes
added the relevant form, html, js, and css for the new api
updated the tornado updates api to accept data for when nodes are edited/updated
added the notes field to be stored in the json_safe of a systemnode object in both text and html format for the frontend to display
updated the systemnode delete api to also delete all related systemconnection objects
adjusted some of the forms to only call their super's clean method if there aren't any errors at that time and return immediately if there are
added an updatenode js function to handle node editing and when node edit broadcasts are received
refactored the js for the add system click handler so it can be used for edit system
changed a lot of raphael element attr calls to take simple values rather than creating an inline object to pass in