[5.5] Don't try to drop Views when executing MySqlBuilder::dropAllTables()

[j859823]

The current MySqlBuilder::dropAllTables() function used by migrate:fresh uses "SHOW TABLES" and issues a "DROP TABLE" Query for all returned Values. This causes MySQL errors once a view exists in the database used for Laravel, as Views can only be droped by "DROP VIEW".

Not sure if using Views is a covered Use-Case for Laravel, but figured i might aswell submit a fix for it.

MySQL Documentation at https://dev.mysql.com/doc/refman/5.7/en/show-tables.html on SHOW TABLES:
"This statement also lists any views in the database. The optional FULL modifier causes SHOW TABLES to display a second output column with values of BASE TABLE for a table and VIEW for a view. "

[taylorotwell]

@freekmurze may have some feedback here.

[freekmurze]

In the laravel-migrate-fresh package we used a query to fetch the names of all real tables.