Merge pull request #1 from tnguyen14/promise

Use promise
default to budget account with period length of 4
sort transactions by date
limit transactions within current week
transactions for next week(s)
consolidate week offset
use mongod
ensureindex
done instead of then for router
use new promise-based mongod for accounts
add lodash
use mongod for transactions
fix bug with showAccount
fix ObjectID error, no longer requires mongodb
clean up
clean up dependencies