Issue title: Add - Trakt List "Unable to connect to list: HTTP request failed"
 Issue body: ### **Describe the bug...**
When adding a "UserCustomList" Trakt List, testing fails and 3 entries are written to the logs

### **To Reproduce...**
Steps to reproduce the behavior:
1. Navigate to and login to https://trakt.tv/auth/signin
2. Go to Lists, then 'ADD LIST'
3. Add _Name_ (no spaces), Privacy to _Public_, Comments to _No_, Default Sorting to _Title_, Click _SAVE LIST_
4. Search for movie in Trakt and add to list created in Step.3
5. Login to Radarr
6. Go to Settings > Lists > Lists > click '+' button > click 'Trakt List' button
7. Change _Name_, Add Movies Monitored to _Yes_, Quality Profile to _Custom_, Folder to _movies folder on NAS_, List Type to _UserCustomList_, Username to _Trakt Username_, List Name to _Name from Step.3_, Click _Test_
8. See screenshots and log for what happens next!

### **Expected behavior...**
Radarr will access and import the Trakt Custom User List successfully for downloading.

### **Screenshots...**
![image](https://user-images.githubusercontent.com/53667144/65396865-4ae53100-ddee-11e9-90ff-2d87dd05bf7b.png)

![image](https://user-images.githubusercontent.com/53667144/65396868-56d0f300-ddee-11e9-8201-551cc0f21113.png)


### **Desktop (please complete the following information)...**
 - OS: Windows 7
 - Mono Version: 116.69.203.115-12
 - Browser and Version: IE (32bit) 11.0.9600.19463 | FF (64bit) 69.0.1 | Chrome (64bit) +1-916-248-0955
 - Version: +1-916-248-0955

### **Debug Logs...**
see here --> [radarr.debug.txt](https://github.com/Radarr/Radarr/files/3640364/radarr.debug.txt)
 Comments: 
 Comment 0: Issue-Label Bot is automatically applying the label `bug` to this issue, with a confidence of 0.85. Please mark this comment with :thumbsup: or :thumbsdown: to give our bot feedback! 

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 Comment 1: Believe this is related to #3779
 Comment 2: I was wondering if it was, however, since this issue is happening in another area of Radarr I thought it might be good to bring it up all the same.

I guess, suffice it to say then that _all_ Trakt integration with the current version of Radarr is broken then??
 Comment 3: I don't think this is related to the other issue.
 Comment 4: This issue has been automatically marked as stale because it has not had recent activity. Please verify that this is still an issue with the latest version of Radarr and report back. Otherwise this issue will be closed.

{'source': 'GithubIssues', 'repo_name_with_owner': 'Radarr/Radarr', 'issue_id': 496857022, 'repo_stars': 7012.0}