Initial pass at implementing journal entries.
Added section to README about persisting the access credentials
include sales receipt instructions in readme
Merge pull request #109 from bhaity/readme_updates

include sales receipt instructions in readme
Adds Entity model and journal entry line detail.
Merge branch 'master' of https://github.com/ruckus/quickbooks-ruby into journal-entry

# By Cody Caughlan (4) and others
# Via Cody Caughlan (4) and bhaity (1)
* 'master' of https://github.com/ruckus/quickbooks-ruby:
  include sales receipt instructions in readme
  Added section to README about persisting the access credentials
  Add AutoDocNumber support to SalesReceipt. Closes #105
  ensure line items initialization when creating new sales receipt
  version bump
  formatting cleanup
  Search_name_query shouldn't be private.
  Make sure all service model classes are marked as private.
  Move default_model_query to BaseService class.
  Make all BigDecimal :to_xml use the to_xml_big_decimal helper method.
Indicate that journal entries are implemented in the readme.
Support preferences endpoint
Update README to indicate which parts of Preferences endpoint are supported
Merge pull request #112 from markrickert/journal-entry

JournalEntry implemented
Merge pull request #115 from nikz/support-preferences-endpoint

Support preferences endpoint
Add DepartmentRef to CreditMemo model.
allow full deletion of credit memos.
Update readme for CreditMemo deletion.
Merge pull request #116 from markrickert/credit-memo-department-ref

Add DepartmentRef to CreditMemo model.
Merge pull request #117 from markrickert/credit-memo-delete

Allow full deletion of credit memos.
Currently an empty line item returns an error validation message as so:
"Line items is too short (minimum is 1 characters)". Kind of confusing
with the "characters" reference. I made the message more
clear. Moreover, I created a module where reusable validations can find a home.
Add Validator module
Merge pull request #118 from minimul/line-err-msg

Currently an empty line item returns an error validation message as so:
version bump for 0.1.3