graham-dds 7a0dc4d264 Add properties to portfolio model
1. Funding duration

Returns a tuple of the earliest period of performance start date and
latest period of performance end date for all active task order in a  portfolio.

2. Days to funding expiration
Returns the numbei of days between today and the lastest
period performance end date of all active task orders

3. Active task orders
Returns a list of a portfolio's active task orders a
2019-11-25 13:12:35 -05:00
..
2019-11-12 16:59:22 -05:00
2019-11-25 13:12:35 -05:00
2019-02-25 14:54:14 -05:00
2018-08-02 16:03:54 -04:00