[2.6b3, websocket, ESXi] Adding a disk to an existing datastore

[Andres Rodriguez]

Problem:

When calling the `update_vmfs_datastore` method with the given params I get an error back in the console with the datastore_id. I am not sure if the params are set up correctly.

Potential solution:

The datastore_id that is being sent is incorrect. This is due to an oversight on my part. When the websocket dehydrates block devices it dehydrates the virtual block device for the VMFS datastore giving it the virtual block device ID, not the datastore id.

I see two ways to fix this on the back end

1. The simple way would be to search for the virtual block id or the datastore id. This[1] patch does that but its still failing. For some reason the UI is sending an invalid partition to remove as well.
2. Specifically dehydrate VMFS. We do this for LVM and Bcache already. This may change how the data over the websocket needs to be read.

I apologize for the oversight.