Plug in Synapse login as part of project initialization

[hafen]

It would be very convenient not to have to add the lines

import synapseclient
syn = synapseclient.Synapse()
syn.login()

to the top of every analysis script, but instead have this called whenever a project is loaded, handling the case where it's the first time a user has logged in and therefore might need to be interactively prompted for their username and password.