Use singleTask for Guide view/create activities

Hopping between guide view and step edit activities using the
singleTop/standard launch modes would add each instance of the activities to
the stack.  This caused some interesting problems with stale data with the
actions Edit > View > Edit > Save > View > Edit > Back > Back > Edit >
Save would cause a 409 since the Edit activity in the back stack does not have
the current revisionid.

Really what we want is only one instance of each guide view/edit activities,
which prevents this stale data problem from happening as well as the annoying,
seemingly pointless jumps between view/edit when going back multiple times.