Enable functionality to clone a jira card

[maxim-kuvyrkov]

Can jipdate be improved to support cloning of a card like what jira's "Clone" functionality provides? I.e.,
jipclone.py --template EXISTING_CARD --summary "New Summary"
Jipdate supports creating new jira cards, but that requires providing information about many relevant aspects of a card -- card type, parent/epic link, status, etc. In certain cases (e.g., CI) it is more convenient to clone a card from a template.

Consider https://linaro.atlassian.net/browse/GNU-834 -- this card hosts sub-task cards for problems detected by Linaro TCWG CI. We want to have CI create these sub-task cards automatically, rather than human copy-pasting information from CI reports. Hard-coding data for sub-task cards in our CI scripts would be sub-optimal, since several fields change regularly -- e.g., parent card, assignee.