restructure activity form/separate from page call

when moving between contacts and creating activities, the contact id and activity id are sometimes lost, or revert to a previous record recently visited. the activity itself does not seem to be affected – it saves to the correct record. but the redirection after submit gets messed up.

the root of the problem seems to be that the activity form is called from the page. because the page session is not always reset, redirection after submit will sometimes retrieve and use a stale contact id from the page session. the behavior is particularly common if the user is working in multiple tabs, though it can be reproduced fairly consistently within a single tab

an attempt to fix that improves the behavior but not 100% is here: http://pastebin.com/7XtKMgxc

lobo's recommendation was to break out the form so it's called separately – not via the page