Running two local servers in development

Use METEOR_LOCAL_DIR to ensure that they don't try to lock the same files, and crash.

# Start first one normally, will build in .meteor/local
meteor run --settings app1-settings.json
# Start second on port 4000 using .meteor/local2
METEOR_LOCAL_DIR=.meteor/local2 meteor run --settings app2-settings.json --port 4000