core: Fix race detected by go race detector
local: remove annoying debug message
Make tests for each Fs

Factor tests out of rclonetest
swift: return directories without / in ListDir
local: fix unit tests

  * Change log.Printf into fs.Log
  * Re-read metadata on SetModtime
s3: strip trailing / from ListDir()
Fixes after running errcheck
Automatically generate the tests files for each Fs
google cloud storage: fix ListDir on subdirectory
google cloud storage: re-read metadata in SetModTime
fs: Document that Purger returns error on empty directory, test and fix
s3: make reading metadata more reliable to work around eventual consistency problems
drive: reset root directory on Rmdir and Purge
all: make private functions / variables / constant which shouldn't be public
Skip tests if test remote not configured
Add Root List test and fs.Limited tests for single files
Test Listing the Root of each Fs