Changed User class function params

Changed addon, chart and document function param in the User class from $ledger_id to $user_id to reflect values being passed.
Added ledger function to the User class

This will create a new instance of the User\Ledger class so you can get ledgers that belong to a user.
Added $addon_id

The addon Id is now to be passed when a new instance of the addon class is created to reflect the end point that is being created.
Added $chart_id

The addon Id is now to be passed when a new instance of the addon class is created to reflect the end point that is being created.
Added $document_id

The document Id is now to be passed when a new instance of the document class is created to reflect the end point that is being created.
Added $report_id

The report Id is now to be passed when a new instance of the report class is created to reflect the end point that is being created.
Added $ledger_id

The ledger Id is now to be passed when a new instance of the ledger class is created to reflect the end point that is being created.
Added $user_id and constructor

The user Id is now to be passed when a new instance of the user class is created to reflect the end point that is being created.
Added required ids for functions
Defaulted Ids to null

In constructors and functions defaulted the id to null, so an id does not need to be required everytime as there are some cases where the id isn't needed. Added comments to reflect and explain this.
Added associated id to the required class and functions
Changed Code Comments and where the ids default
Added comments and defaulted $ledger_id to null
Update of comments
Update of code comments
Updated Code comments
Added Code comments and made id optional
Defaulted ids to 'current'
Dedfaulted Ids to 'current'
Merge branch 'feature/feature-refactor-ids' into develop