Remove use of 'fsutil' during Windows detection

[bridadan]

Should fix #263 and #264.

In #241, I modified the detection process for Windows to use the fsutil program that ships with Windows. It provides a very fast way to detect what drive letters are currently available on the system. However, I missed this very important fact (spelled out in plain ol' English on their doc page):

You must be logged on as an administrator or a member of the Administrators group to use fsutil. The fsutil command is quite powerful and should be used only by advanced users who have a thorough knowledge of Windows operating systems.

😞

This PR changes the drive detection to the following:

• Take the results that are returned from the registry query
  • This includes mountpoints that may or may not be present on the system
• Loop over each mountpoint and call the Windows dir command
  • If it fails, don't include it in the returned list
  • The downside to this approach is we have to make more system calls
    • "But why not just use os.path.exists ?!?!"
    • If you call that function on a drive that is in the ejected state (happens directly after flashing), Python will throw a blocking error box and halt, and the workaround isn't that great
  • The upside is this doesn't require administrator privileges

FYI @toyowata @MarceloSalazar

[bridadan]

Could you please review @theotherjimmy ?

[bridadan]

Well that's weird, works just fine on my Windows box. I'll try it in my VM.

[theotherjimmy]

Could you move this function outside of the test?

[coveralls]

Coverage decreased (-0.7%) to 73.272% when pulling 87af6d1 on bridadan:no_fsutil_win_detection into 3dfbc83 on ARMmbed:master.

[theotherjimmy]

Thanks for the update. @MarceloSalazar You could use a new release with this change set correct?

[bridadan]

Thanks for the update. @MarceloSalazar You could use a new release with this change set correct?
@theotherjimmy my understanding is he has a workshop to put on so yes to a new release!

[MarceloSalazar]

Thanks @bridadan @theotherjimmy for the quick fix!
I confirm v1.3.4 works well on Windows 7 :)

[toyowata]

@bridadan @theamirocohen me too!! Thanks for your fix! :-)

[bridadan]

Great to hear, thanks for testing @MarceloSalazar and @toyowata!