Features/bdd journal format.feature

This successfully implements `features/journal_format.feature`

```
prompt> behave  features/journal_format.feature 
Feature: Opening, Reading and Importing General Journal # features/journal_format.feature:1
  As a user of Lemonade, I want to be able to read my General
  Journal. I may edit it manually and I still want it to be
  function like normal in Lemonade.
  Scenario: General Journal has a title                                     # features/journal_format.feature:6
    Given I have a General Journal File                                     # features/steps/journal.py:28 0.000s
    When the first row is read                                              # features/steps/journal.py:34 0.000s
    Then the title of the journal will be on the first row and first column # features/steps/journal.py:51 0.000s

  Scenario Outline: General Journal has headers              # features/journal_format.feature:11
    Given I have a General Journal File                      # features/steps/journal.py:28 0.000s
    When the third row is read                               # features/steps/journal.py:34 0.000s
    Then the header 'Date' will be in column 'A' of that row # features/steps/journal.py:58 0.000s

  Scenario Outline: General Journal has headers                       # features/journal_format.feature:11
    Given I have a General Journal File                               # features/steps/journal.py:28 0.000s
    When the third row is read                                        # features/steps/journal.py:34 0.000s
    Then the header 'Account Title' will be in column 'B' of that row # features/steps/journal.py:58 0.000s

  Scenario Outline: General Journal has headers                   # features/journal_format.feature:11
    Given I have a General Journal File                           # features/steps/journal.py:28 0.000s
    When the third row is read                                    # features/steps/journal.py:34 0.000s
    Then the header 'Post Ref.' will be in column 'C' of that row # features/steps/journal.py:58 0.000s

  Scenario Outline: General Journal has headers               # features/journal_format.feature:11
    Given I have a General Journal File                       # features/steps/journal.py:28 0.000s
    When the third row is read                                # features/steps/journal.py:34 0.000s
    Then the header 'Debit' will be in column 'D' of that row # features/steps/journal.py:58 0.000s

  Scenario Outline: General Journal has headers                # features/journal_format.feature:11
    Given I have a General Journal File                        # features/steps/journal.py:28 0.000s
    When the third row is read                                 # features/steps/journal.py:34 0.000s
    Then the header 'Credit' will be in column 'E' of that row # features/steps/journal.py:58 0.000s

  Scenario: 'Date' field is populated in the first line item of a General Journal entry  # features/journal_format.feature:24
    Given I have a General Journal File                                                  # features/steps/journal.py:28 0.000s
    When I read a journal entry                                                          # features/steps/journal.py:66 0.003s
    Then column 'Date' will be populated in the first line item and no other             # features/steps/journal.py:73 0.000s

  Scenario: 'Account Title' is only field populated on the last line item of a General Journal entry  # features/journal_format.feature:29
    Given I have a General Journal File                                                               # features/steps/journal.py:28 0.000s
    When I read a journal entry                                                                       # features/steps/journal.py:66 0.000s
    And I have the last line of that entry                                                            # features/steps/journal.py:79 0.000s
    Then column 'Account Title' will be populated on that line                                        # features/steps/journal.py:92 0.000s
    And no columns except 'Account Title' will be populated on that line                              # features/steps/journal.py:97 0.000s

  Scenario: All Journal entries should have line items with 'Account Title's                              # features/journal_format.feature:36
    Given I have a General Journal File                                                                   # features/steps/journal.py:28 0.000s
    When I read a journal entry                                                                           # features/steps/journal.py:66 0.000s
    Then each line item in that journal should have the 'Account Title' field populated                   # features/steps/journal.py:106 0.000s
    And each line item in that journal (except the last line) should have the 'Post Ref.' field populated # features/steps/journal.py:112 0.000s

  Scenario: All Journal entries should have equal sum of debits and sum of credits                        # features/journal_format.feature:42
    Given I have a General Journal File                                                                   # features/steps/journal.py:28 0.000s
    When I read a journal entry                                                                           # features/steps/journal.py:66 0.000s
    Then each line item in that journal (except the last line) should have either a Debit or Credit entry # features/steps/journal.py:118 0.000s
    And the sum of the 'Debit' column should equal the sum of the 'Credit' column.                        # features/steps/journal.py:126 0.000s

1 feature passed, 0 failed, 0 skipped
10 scenarios passed, 0 failed, 0 skipped
34 steps passed, 0 failed, 0 skipped, 0 undefined
Took 0m0.007s
```