filtering in the wrong place

[tromp]

Solution filtering would preferably be done at a higher level in src/bin/mining.rs

The current filtering cuckoo-miner/src/miner/miner.rs subverts the notion of a solution,
making what's called a solution into a cyclehash share, and hides the number of solutions
from higher levels. This prevent the reporting of an accurate fidelity in src/bin/mining.rs