Remove core instance dependency at plugin level

[mihaidma]

The purpose of this PR is to remove the dependency on a common Udaru Core instance passed as parameter to routes and other functionality at the plugin level.

The changes are the following:

• All routes expect a decorated Udaru instance on request,
• Routes Joi validation is used by directly requiring the Joi validation files. Validation is not gathered any more from a common Udaru instance,
• The authorization checks made at route level are using the Udaru core instance decorated on request
• The service has an option with wich the Udaru core decoration can be disabled (it is enabled by default). This allows Udaru core to be passed from outside from the service level.
• Added a small change on the Factory used by tests to generate data in db. As it was using a default Udaru core (with default settings) added the possibility to pass the Udaru core instance from outside.

While doing the changes did also two fixes:

• A db pool passed from outside should not be released by Udaru core,
• config params were not properly passed from the plugin level to Udaru core level.

This dependency removal offers the users of Udaru the option to pass from outside their own Udaru core instance and in a multitenant environment pass different per tenant Udaru core Instances on each request. #430

Each step is made as a separate commit to make the review easier.

[coveralls]

Coverage decreased (-0.05%) to 96.397% when pulling ddf0b59 on issue-430-connections-decorated into 55767b4 on master.

[dberesford]

All looks good to me @mihaidma

[coveralls]

Coverage decreased (-0.05%) to 96.397% when pulling 349a05f on issue-430-connections-decorated into 55767b4 on master.

[paolochiodi]

Looks good to me.

I usually prefer explicit dependencies (in function parameters) to "hidden" dependencies using (i.e using request decoration), but I understand this is required to be able to use a different udaru core on different requests.

👍

[paolochiodi]

shouldn't we also remove config here and use the decorated one?

[mihaidma]

👍 As the PR got big I'll merge it then see what enhancements we can come up with.