Allow control over commit periods

[hesterbruikman]

User story

• As a funder I want to be able to specify a commit period in which I can veto (#87) a pledge to a project down the pledging chain

Current default is set to 3 days (72h)

Implementation

Further specify what commit periods can be set during project creation and to what extend a funder can influence the commit period before pledging.

• Set commit period in project creation flow
• Approve or propose commit period in funding flow

Acceptance Criteria

Notes

Future Steps