Refactor configuration variables

[inakianduaga]

Drivers should have API for configurable properties (basePath for file/AwsS3, S3 bucket/credentials for AwsS3, etc.

That way each model can configure the driver instance it uses in whatever way it wants. The alternative is to provide a config key on the model that is passed to the driver and the driver uses that for configuring itself

Update:

• Remove Model reference from the drivers (single-responsability, the driver shouldn't have to give a crap about what the model is).
  • Move the storage setPath update to the actual boot observer method.
• Add abstract driver implementation
  • Extract the generateStoragePath method which is always the same
• Add storageDriverConfigKey property on the trait, that's the only property we will need to set on the model so the driver/adaptor can be integrated.
• Add a setConfigKey() method to the driver interface (& abstract implementation)
• On boot method of trait, add after parent::boot() a

$storageDriver = app(StorageDriver::class)->setConfigKey($this->storageDriverConfigKey); 

Use this on the creating/deleting methods (remember to pass the variable to the lambda function)  

• Move the $binaryPathDBField from the trait to a config property, that way we use only a single key to reference to the config, and everything else is read from there.