fix advanced_settings_purposes_default with custom purposes (#241)

[atoiv]

Hi,

This pr should fix #241. It makes config option advanced_settings_purposes_default=true to also work with custom purposes.

This appeared to be a rather straightforward fix, and as far as I looked, it didn't affect anything else than the exact functionality with the advanced_settings_purposes_default option, when the option is enabled.

Tests were green after the change.

[coveralls]

Pull Request Test Coverage Report for Build 863

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 26.346%

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Totals
Change from base Build 862:	0.0%
Covered Lines:	1101
Relevant Lines:	3386

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💛 - Coveralls

[JeppeSigaard]

@atoiv This is great! can you solve the merge conflicts?
@Waschnick what would be required to get this into a release?

[atoiv]

Sorry it took a while to check back on this. It seems I've missed all the notifications for the PR.

The merge conflicts are now solved.

[atoiv]

It seems reading custom purposes from a cookie is also broken. I have a local fix for that, but I'll look into adding it here as well, after I get time to do it.

Edit: Yikes, pushed send too fast!

Meant to ask if I should add the code to that fix here as well, or create a new PR? The changes are close to the ones made for this one.