Revert "extent of scale needs to cover all TAZs; raise max to 6m, adjust scale to fit nicer"

This reverts commit 69061fffcfc11aa1d1b6b7c9ff1db7ffee5d5a4f.
Revert "change housing price scale to max at 5m"

This reverts commit 96fc565990f0b074cd3d714a5917f92c910adedc.
don't hardcode max price of housing data.
Merge branch 'master' of github.com:MetropolitanTransportationCommission/travel-housing-map