Need even friendlier keyring errors

[major]

The start of this was added in 393eed2 but it needs further refinement. Showing a full exception to a user isn't desirable. :/

[FancyFane]

Hi major,

To add to this open issue, I'm currently getting an error that ends with "No Recommended backed available" I'm not sure what is needed here to resolve this issue.

$ supernova-keyring -s mycloud OS_PASSWORD

Preparing to set a credential in the keyring for:

  - Environment  : mycloud
  - Parameter    : OS_PASSWORD

If this is correct, enter the corresponding credential to store in your keyring
or press CTRL-C to abort: 
Traceback (most recent call last):
  File "/usr/bin/supernova-keyring", line 9, in <module>
    load_entry_point('supernova==2.2.0', 'console_scripts', 'supernova-keyring')()
  File "/usr/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/core.py", line 716, in __call__
    return self.main(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/core.py", line 696, in main
    rv = self.invoke(ctx)
  File "/usr/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/core.py", line 889, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/core.py", line 534, in invoke
    return callback(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/click-6.2-py2.7.egg/click/decorators.py", line 17, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/supernova/executable.py", line 286, in run_supernova_keyring
    password=credential)
  File "/usr/lib/python2.7/site-packages/supernova/credentials.py", line 94, in set_user_password
    return password_set(username, password)
  File "/usr/lib/python2.7/site-packages/supernova/credentials.py", line 102, in password_set
    result = keyring.set_password('supernova', username, password)
  File "build/bdist.linux-x86_64/egg/keyring/core.py", line 48, in set_password
  File "build/bdist.linux-x86_64/egg/keyring/backends/fail.py", line 18, in get_password
RuntimeError: No recommended backend was available

[FancyFane]

Hi Major,

I wanted to follow up on this issue.

$ pip2 freeze | grep keyring
keyring==8.0.1

This version of keyring is causing problems, I've installed version keyring==5.6 and the "No Recommended Backend" error went away.

$ pip2 freeze | grep keyring
keyring==5.6

[major]

This may help if you want to stay on keyring 8.0+:

pip install keyrings.alt

The file-based keyring storage was removed from the 8.x version. I'm going to set a cap on the keyring module in the hopes that it will help this issue until I can get a long-term fix.