[FIX] Fix computation in initial_balance in open invoices and partner_ledger report
[IMP] - product_barcode_report: Set report default to database.

Set the report template encoded as base64 string and changed source to database.
[FIX] - account_invoice_partner_date_due: Fixes #39, Out of range error

Deleted one method and did the override inside onchange_partner_id method taking care of validations.
[IMP] - account_invoice_partner_date_due: Removed unused imports.
Merge pull request #40 from CLEARCORP-dev/7.0_account_invoice_error

[FIX] - account_invoice_partner_date_due: Fixes #39, Out of range error.
Merge pull request #38 from CLEARCORP-dev/7.0_product_barcode_report

[IMP] - product_barcode_report: Set report default to database.
Merge pull request #37 from CLEARCORP-dev/7.0-fix_open_invoices_partner_ledger_report-dr

[FIX] Fix computation in initial_balance in open invoices and partner_le...