Fail to start with SQL store with MySQL server 8.0.2

[kozlovic]

@camsjams Reported this issue in #533

MySQL 8.0.2, (docker image - mysql:8.0.2)
Nats 0.9.0 ( docker image - nats-streaming:0.9.0)

2018/03/29 19:39:22.709350 [INF] STREAM: Starting nats-streaming-server[test-cluster] version 0.9.0
2018/03/29 19:39:22.709553 [INF] STREAM: ServerID: dutqmYYUX3kNfne308YBqk
2018/03/29 19:39:22.709566 [INF] STREAM: Go version: go1.9.4
2018/03/29 19:39:22.721593 [INF] STREAM: Shutting down.
2018/03/29 19:39:22.721640 [FTL] STREAM: Failed to start: unable to prepare statement "INSERT INTO SubsPending (subid, row, seq) VALUES (?, ?, ?)": Error 1064: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'row, seq) VALUES (?, ?, ?)' at line 1

As he reported, we may need to change the following:

nats-streaming-server/stores/sqlstore.go

Lines 121 to 124 in 4380598

	"INSERT INTO SubsPending (subid, row, seq) VALUES (?, ?, ?)", // sqlSubAddPending
	"INSERT INTO SubsPending (subid, row, lastsent, pending, acks) VALUES (?, ?, ?, ?, ?)", // sqlSubAddPendingRow
	"DELETE FROM SubsPending WHERE subid=? AND seq=?", // sqlSubDeletePending
	"DELETE FROM SubsPending WHERE subid=? AND row=?", // sqlSubDeletePendingRow

Need to check the effect of Postgres driver.