Added receipts_pdf.py

Used Paragraph for displaying a large body of text.

added the table

Line breaks in the para text. font size adjusted.

Improved the main table (alignments) and totals (converted to a table as well)

Converted the footer into a table, and allowed for pagination.

Added pagination to item data table.

Handled wrapping of long descriptions into multiple lines.

email attachment for both invoice and receipt

added the currency from the settings

Removed magic numeric literals and added meaningful variables.

Added initial set of substitutions from configuration

add defining logo paths via configuration

Removed font dependencies. Will use the system default fonts which appear good enough to me.

Alignment adjustments as per suggestions.

Fixed the pep8 violations. Added comments to styling

added the decimal points to the price values

Cleanup. Docstrings.

i18n the text in the pdf file

fix pep8/pylint issues

Changed the amounts from string to float.

Overrode the 'pdf_receipt_display_name' property in the OrderItem subclass Donation.

used the PaidCourseRegistration instead of the parent OrderItem to avoid course_id related exceptions.

quality fixes

added  the test cases for the pdf

made the changes in the pdf suggested by griff

updated the pdf tests to assert the pdf content

used the pdfminor library

fix quality issues

made the changes suggested by Will

added the text file that says "pdf file not available. please contact support"
 in case pdf fails to attach in the email