Improved Status Reports

[WhoSoup]

closes: #46

Per #46, we really need better reporting. This PR does the following:

• If the node is up to date on boot, it will print: level=info msg="Node is up to date" height=XXXXXX
• If it's the intial sync, or there are > 1 blocks to sync, it will print a message before and after the sync loop: level=info msg="Starting sync job of XXX blocks" height=AAAAAA target=BBBBBBB and level=info msg="Finished sync job" blocks-synced=XXX height=BBBBBBB
• Instead of reporting sync stats every 50 blocks, it will report them every 15 seconds
• Under normal operations (not syncing more than one block at a time), print out a "status report" with current height every 6 blocks (height%6 == 0), which should be roughly once an hour

edit: fixed link to right issue

[WhoSoup]

Example outputs

time="2019-10-30T12:17:58+01:00" level=info msg="Listening on :8070..."
time="2019-10-30T12:17:58+01:00" level=info msg="Starting sync job of 291 blocks" height=216273 target=216564
time="2019-10-30T12:18:13+01:00" level=info msg="sync stats" avg=188.773297ms elapsed=15.1018638s height=216353 left=39.831165667s syncing-to=216564
time="2019-10-30T12:18:28+01:00" level=info msg="sync stats" avg=186.041504ms elapsed=30.1397239s height=216435 left=23.999354016s syncing-to=216564
time="2019-10-30T12:18:43+01:00" level=info msg="sync stats" avg=184.120286ms elapsed=45.2955908s height=216519 left=8.28541287s syncing-to=216564
time="2019-10-30T12:18:52+01:00" level=info msg="Finished sync job" blocks-synced=291 height=216564

and

time="2019-10-30T12:30:07+01:00" level=info msg="Listening on :8070..."
time="2019-10-30T12:30:07+01:00" level=info msg="Node is up to date" height=216565
time="2019-10-30T13:14:58+01:00" level=info msg="status report" height=216570
time="2019-10-30T14:14:59+01:00" level=info msg="status report" height=216576