Configurable buffer minutes added to travel time

Allow padding travel time estimates by a configurable number of minutes, since travel time means different things for different people. If someone is getting directly into their car from their home, the estimate is correct, but some people may wish to pad the time by a certain amount to factor for elements like:

• Taking 5 minutes to prep to leave the house

• Walking a distance to a parking space

• Leaving a large office building

• Peace of mind