Gitless crashes if there's a directory it can't read in the repo.

[skorokithakis]

There's a directory in a repo that my user doesn't have permission to read, and gitless does not like it at all:

> gl status
  Traceback (most recent call last):
    File "/home/santiago/Documents/code/gitless/build/gl/out00-PYZ.pyz/gitless.cli.gl", line 69, in main
    File "/home/santiago/Documents/code/gitless/build/gl/out00-PYZ.pyz/gitless.cli.gl_status", line 45, in main
    File "/home/santiago/Documents/code/gitless/build/gl/out00-PYZ.pyz/gitless.core", line 752, in status
  OSError: Failed to open directory 'dbdata/': Permission denied