User layer between make_quote.py and user

[sumeetkd]

Moving all the functions from make_quote.py to a separate layer

[chintal]

The quotation layer should go into tendril-sales and be available from tendril.sales.quotation

Example (non-functionalized on purpose) of make_quote.py.

Use of third-party identities will be required for this to be worth the effort. I will open another issue for that dependency and refer that here.