time based election

[OdedWx]

Description

Change of the election schedule to be based on time instead of Ethereum blocks to provide a more consistent and easy to understand schedule. Election schedule - every 3 days based on the Ethereum block time to enable external auditing Vote validity - up to 1 week

Types of changes

What types of changes does your code introduce? Put an x in the boxes that apply

• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)

[noambergIL]

should be merged to master + make sure the network-go vendor points to master when the network-go review of the election contract is done :)