Adds simple handler to provide failed line numbers
Adds simple handler to provide failed line numbers

Change adds `as err` handler to provide line number, if config yaml
fails to parse.

Example output

[config]  ERROR   while scanning a simple key
  in "config.yaml", line 5, column 1
could not find expected ':'
  in "config.yaml", line 6, column 1
[main]  ERROR   config.yaml : Error parsing file.

Change-Id: If764a123c0dd8871dcd98f58be48c6bf0034f1d4
Closes-Bug: #1621552

chair6/bandit,stackforge/bandit,pombredanne/bandit,stackforge/bandit,pombredanne/bandit