This patch adds a `bank_import` app which allows users to upload and
import their Bank Statements. After uploading a bank statement(in CSV or
QFX format), the application presents a form where accountants can add
any entries from the statement that have not been entered into the
system yet. Entries may have their account, memo and payee/payor
prefilled if there are similar entries from previous months.

Accountants can add ranges of check numbers that are automatically
assigned an Account, Memo, & Payee.

Currently only Virginia Community Bank & City First - Bank of DC are
supported, but there is a BaseImporter class that may be subclassed to
add additional banks.

Closes #141