This is a port of @avsa's contribution from his proposed offer contract
that can be seen here:
https://gist.github.com/alexvandesande/122c05a0f8a7108523aed29ae7ec92b1

At any point `voteStatusDeadline` seconds before the end of the voting
period anyone can call `checkVoteStatus()` to attempt and set the
`wasApprovedBeforeDeadline` flag.

This allows for a way to assure that the last minute yes vote does not
occur by requiring the flag to be set to true at an earlier point of the
voting deadline.

A test that the checkVoteStatus will fail if it is called after the
`voteStatusDeadline` period

Adding the watchProposal() function that @alexvandesande introduced in
his Sample Offer contract
[here](https://gist.github.com/alexvandesande/122c05a0f8a7108523aed29ae7ec92b1#file-proposal-js-L271).

This way there is no requirement to pass the `proposalID` as a
constructor argument. The contractor should instead add it on his own
after he makes the proposal by calling `watchProposal()`.

If the contractor tries to cheat by making 2 or more different proposals and
adding the one that has gotten the most votes as the proposal ID in
`watchProposal()` the token holders will notice and raise the alert so
that the contractor can be blacklisted.