GetFileIDs tests

Prerequisites: A least 2 different files are are present in the collection. 

List all files

1. Request listing of all files
   1. The existing files in the system should be listed with their size and a count of pillars where the file is present.

List known file

1. Request listing of a single existing file, see it comes back in the listing with the correct file size and pillar count.

List unknown file

1. Request listing of a file not in the collection.
   1. An empty list is returned.

Missing files

1. Put a new file to a single pillar
2. Request listing of all files.
   
   1. Verify that the new file is present on all pillars and that they agree on its size.
3. Delete the file on one or more pillars.
4. Request listing of all files.
   
   1. Verify that the pillar count for the file reflects the number of deletions, and that the original set of files is still listed.
5. Delete the new file on the remaining pillars.
   
   1. Verify that the all the pillars only list the original files.

Bad arguments

1. Try getting all file ids from a non-existing collection
   
   1. Should fail with an error telling the existing collections.
2. Try getting the file ids from a non-existing pillar
   
   1. Should fail with an appropriate error containing the existing pillars
3. Try getting a file from a pillar in a different collection
   
   1. Should fail with an appropriate error containing the existing pillars for the collection