Report Column Headers for Custom Fields should use the Label field by default

[#1]

With the new API-friendly option for custom fields, I have found an issue with the default display of custom fields in reports.

Columns headers should be user-friendly by default, not system friendly. Thus, they should use the label by default as that is what the average user is aware of.

[#2]

For context we have a custom field that has a label of "Content Class" but an internal name of "contentClass"

Anytime we add that field to a report we will have to manually add a custom display name to get it to display in a user-friendly manner.

Additionally, this makes searching for these custom fields more difficult as it only returns results that match the first set of characters.