Update for MySQL 5.7 and above

[OsandaMalith]

Starting from MySQL 5.7 the 'password' column was changed to 'authentication_string'. I've added a check to determine the version. If the version is higher than 5.6 the column 'authentication_string' will be used instead of 'password'. Tested on both MySQL 5.6 and 5.7.

The bug due to non existence of 'password' column in MySQL 5.7:

[busterb]

@OsandaMalith you'll want to check the result of the automated checks above and resolve them. To test locally, run ./tools/dev/msftidy.rb modules/auxiliary/scanner/mysql/mysql_hashdump.rb

[busterb]

See 1bb5499, I went ahead and fixed some of the minor style issues in the module and made the linter happy.

Thanks a lot for the update @OsandaMalith !

[allrosenthal-r7]

@busterb can you please add release notes to the PR?

[allrosenthal-r7]

Release Notes

This fix resolves an issue caused by renaming the 'password' column as 'authentication_string' in MySQL version 5.7 and onwards. The auxiliary/scanner/mysql/mysql_hashdump module now checks the MySQL version and uses the appropriate name for the column.