This helps when the table itself doesn't have foreign keys defined but if there are other tables with foreign keys pointing to the table on which gh-ost runs.
This gives INFO messages for each FK. Note that it now informs the user about `payment` being involved.
```
$ ./gh-ost -database sakila -table rental -alter 'ADD COLUMN ghost_test_001 tinyint DEFAULT NULL' -port 19590 -user msandbox -password msandbox -verbose
2016-08-03 10:18:45 INFO starting gh-ost 1.0.8
2016-08-03 10:18:45 INFO Migrating `sakila`.`rental`
2016-08-03 10:18:45 INFO connection validated on 127.0.0.1:19590
2016-08-03 10:18:45 INFO User has ALL privileges
2016-08-03 10:18:45 INFO binary logs validated on 127.0.0.1:19590
2016-08-03 10:18:45 INFO Restarting replication on 127.0.0.1:19590 to make sure binlog settings apply to replication thread
2016-08-03 10:18:46 INFO Table found. Engine=InnoDB
2016-08-03 10:18:47 INFO Found foreign key on `sakila`.`payment` related to `sakila`.`rental`
2016-08-03 10:18:47 INFO Found foreign key on `sakila`.`rental` related to `sakila`.`rental`
2016-08-03 10:18:47 INFO Found foreign key on `sakila`.`rental` related to `sakila`.`rental`
2016-08-03 10:18:47 INFO Found foreign key on `sakila`.`rental` related to `sakila`.`rental`
2016-08-03 10:18:47 ERROR Found 4 foreign keys related to `sakila`.`rental`. Foreign keys are not supported. Bailing out
2016-08-03 10:18:47 FATAL 2016-08-03 10:18:47 ERROR Found 4 foreign keys related to `sakila`.`rental`. Foreign keys are not supported. Bailing out
```
Related Issue: https://github.com/github/gh-ost/issues/129
Related Issue: https://github.com/github/gh-ost/issues/136
New output:
```
2016-08-05 11:39:07 DEBUG Privileges: Super: true, REPLICATION SLAVE: false, ALL on *.*: false, ALL on `sakila`.*: true
2016-08-05 11:39:07 ERROR User has insufficient privileges for migration. Needed: SUPER, REPLICATION SLAVE and ALL on `sakila`.*
2016-08-05 11:39:07 FATAL 2016-08-05 11:39:07 ERROR User has insufficient privileges for migration. Needed: SUPER, REPLICATION SLAVE and ALL on `sakila`.*
```
- by default gh-ost will not delete an existing socket file
and thus, will fail running if socket file exists. This is the desired behavior.
- The flag --initially-drop-socket-file indicates we take responsibility and wish gh-ost to delete this file on startup
