Automatically generate the "Pivot Model" on "Belongs to Many Relationships", if not informed

[TiagoSilvaPereira]

When informing a belongsToMany relationship on the Project file, and if a pivot table is not specified, create it using:

• The table name will be the name of the two related models alphabetically sorted.
• The table will have two Foreign Keys pointing to the two models PK (considering pk is id at this moment)