Timestamp millisecond conversion to time.Time

[WhoSoup]

Just came across this bug: when converting a factom Timestamp to a Golang time.Time, the milliseconds are not converted correctly. Example:

	fmt.Println(time.Now())
	ts := primitives.NewTimestampNow()
	fmt.Println(ts.GetTime())

Output:

2020-06-29 14:56:43.556323 +0200 CEST m=+0.002009801
2020-06-29 14:56:43.000556 +0200 CEST

The milliseconds shifted from milliseconds to being microseconds. Fortunately, factomd is mostly using Timestamp internally and doesn't convert to time.Time except for a few cases:

• The Live API for admin block event ServerFault, DBlock headers, DBlock anchors, Entry Reveals, and Transactions
• The HoldingList for testing if messages are stale (no major ramifications as long as it's consistent)
• Processlist checking if messages are out of date (no major ramifications as long as it's consistent)
• Message filter (no major ramifications as long as it's consistent)

The fix is incredibly simple: https://github.com/FactomProject/factomd/commit/6b9fde5f9c4e316c5d8dce230ed2421f54dbb7aa

However, this might need to wait for a hard fork to be updated. Some nodes accepting messages that are less than 1ms away from being timed out and other nodes rejecting them could be an attack vector.