`bin/dlog` should promote user to run `mvn install` if the source is not built

[sijie]

BUG REPORT

1. Please describe the issue you observed:

• What did you do?

1. download the source bindary
2. run stream/distributedlog/core/bin/dlog local 7000

• What did you expect to see?

the local emulator started

• What did you see instead?

$ ./stream/distributedlog/core/bin/dlog local
JMX enabled by default
DLOG_HOME => ./stream/distributedlog/core/bin/..
Error: Could not find or load main class org.apache.distributedlog.LocalDLMEmulator

[sijie]

I believe this has been addressed by 7446d5c

[sijie]

Fixed by #1407