Change ConfigException to indent messages after line breaks

[vlovgr]

Messages in ConfigException are now indented after line breaks.

Example before:

ciris.ConfigException: configuration loading failed with the following errors.
  - Failed to parse file at <path> with charset UTF-8:
// TODO
^
expectation:
* must end the string.

Example after:

ciris.ConfigException: configuration loading failed with the following errors.
  - Failed to parse file at <path> with charset UTF-8:
    // TODO
    ^
    expectation:
    * must end the string.