Setting to exclude source folder name from "Remote folder" destination

### Actual behaviour
-Tell us what happens
Under Nexctloud app beta (20170204 and prior), setting up individual Autoupload "Remote folder" is a great idea.
However, I am not happy with the default "InstantUpload" as the primary folder. The reason is that I do share this folder with other people and it does appear under "InstantUpload(2)" and so forth. Thus is not very personal. So to alleviate this shortcoming, I have created a ""InstantUpload_my_account_name" folder on my server.
Where it becomes messy is when I have to change the default "remote folder" location to my own. This is not so much the process that bothers me, but rather the inability to preserve the subfolder structure.
For instance, the default folder for the Camera folder would be set to "InstantUpload/Camera". Will trying to remap the "Remote Folder" to my own, I loose the "/Camera" subfolder.
For now it is not a problem as I do not mind having videos and picture from the camera into the same folder.
I might find some issues is with the other apps.
I use Whatsapp and if I remap the "Remote Folder" to mine, then I loose the "/Whatsapp" subfolder. If I want to retain it's hierarchy, I must enter the name manually.
I wish there was an option to relocate to a different top level folder and still preserve the child folder.
This should be done with a user prompt.

### Expected behaviour
-Tell us what should happen
Upon remapping "Remote Folder" the app should request by providing a prompt to the user whether the child subfolder should be preserved and applied to the new folder.

1: Default folder location under "Remote Folder is "InstantUpload/Camera".
2: I want to remap the location to "InstantUpload_Olivier"
3: I should be asked if I want to preserve the folder structure and have instead "InstantUpload_Olivier/Camera"
4-A: If YES, then "InstantUpload_Olivier/Camera" should be created
4-B: If NO, then "InstantUpload_Olivier" should be used.

This of course is a case by case procedue for every Autoupload source folder.

### Steps to reproduce
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### Environment data
Android version:

Device model:

Stock or customized system:

Nextcloud app version:

Nextcloud server version:

### Logs
#### Web server error log
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#### Nextcloud log (data/nextcloud.log)
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