[AIRFLOW-1712] Log SSHOperator output

SSHOperator does now write stdout to log, just like SSHExecutorOperator
did in the past

[AIRFLOW-1712] Log SSHOperator output

SSHOperator does now write stdout to log, just like SSHExecutorOperator
did in the past

[AIRFLOW-1613] Handle binary field in MySqlToGoogleCloudStorageOperator

Closes apache#2680 from jgao54/write-binary

[AIRFLOW-1671] Add @apply_defaults back to gcs download operator

Closes apache#2655 from jgao54/bug-fix

[AIRFLOW-1356] Add `--celery_hostname` to `airflow worker`

Closes apache#2405 from d2207197/airflow-1356

Set version 1.8.2rc2 -> 1.8.2

Set version 1.8.2rc2 -> 1.8.2

[AIRFLOW-1476] add INSTALL instruction for source releases

[AIRFLOW-756][AIRFLOW-751] Replace ssh hook, operator & sftp operator…

… with paramiko based

Closes apache#1999 from jhsenjaliya/AIRFLOW-756

Updating CHANGELOG for 1.8.2rc2