remove SimpleResultHandler from GrantService; get rid of ServiceCallback

GrantService is a Context, but not the particular kind that lets you open dialog boxes
 opening the "connection error" dialog would cause a crash
this is worked around by making all the activities pass in SimpleResultHandlers instead
reopen log-in screen on "Invalid Session ID" message

this is about the laziest possible way to handle things, as compared to opening a dialog or storing the login details
(both of which would preserve the user's data)
better error logging in jsonparser
manifest edits

go back to the calendar when returning to the app
really, really kill the whole activity on connection error

it turns out, opening another activity from onCreate
(as was happening in MainActivity) is handled specially
so that's why the code to launch the other activities
is in onStart now

the new quit method has been added to CommentDialog, so quitting from
DetailView will be effective