Handle setting flags for tours

[flibbertigibbet]

For multi-stop events and tours, set the flags for the overall tour, either directly as a property of the tour, or based on the constituent destinations. (Flags include things such as: activities available, whether it is accessible, whether it is in the Watershed Alliance).

For some of these, such as activities, we may want to set the flag if the flag is set on any of the constituent destinations. For others, such as accessibility, it might make more sense to only set it if all the constituent destinations have that property.