Config loading - Display specific error message instead of the same error every time on failure

[cham11ng]

Description

Log an exception error instead of same custom error message

Cases:

• boss.yml file not found.

[Errno 2] No such file or directory: 'boss.yml'

• Invalid vault address is set.

Invalid URL 'test/v1/app/dev': No schema supplied. Perhaps you meant http://test/v1/app/dev?

Enable DEBUG flag

$ DEBUG=true fab dev build

Traceback (most recent call last):
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/boss/config.py", line 104, in load
    use_vault_if_enabled(config_str, stage)
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/boss/config.py", line 171, in use_vault_if_enabled
    vault.env_inject_secrets(path, silent=raw_config['vault']['silent'])
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/boss/core/vault.py", line 65, in env_inject_secrets
    secrets = read_secrets(path)
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/boss/core/vault.py", line 35, in read_secrets
    result = client.read(path)
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/hvac/v1/__init__.py", line 157, in read
    return self._adapter.get('/v1/{0}'.format(path), wrap_ttl=wrap_ttl).json()
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/hvac/adapters.py", line 90, in get
    return self.request('get', url, **kwargs)
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/hvac/adapters.py", line 219, in request
    allow_redirects=False, **_kwargs)
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/requests/sessions.py", line 510, in request
    prep = self.prepare_request(req)
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/requests/sessions.py", line 453, in prepare_request
    hooks=merge_hooks(request.hooks, self.hooks),
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/requests/models.py", line 313, in prepare
    self.prepare_url(url, params)
  File "/Users/cham11ng/Source/boss/venv/lib/python2.7/site-packages/requests/models.py", line 387, in prepare_url
    raise MissingSchema(error)
MissingSchema: Invalid URL 'test/v1/app/dev': No schema supplied. Perhaps you meant http://test/v1/app/dev?

[kabirbaidhya]

LGTM! Thanks @cham11ng 👍