There are valid JSON keys which can contain a nested '.' in them.
However, this module would not handle those properly, except in a
limited set of conditions. This commit adds support for these paths when
they are properly escaped using a '\' character. However, this does
slightly change the base functionality for the module where a value with
the same key path as a top-level key with the nested value's key path
will now read the nested value, unless the provided path has appropriate
escaping on the key path.

For example... with the example doc:
    { 'a.b' : 2, a : { b : 3 } }

evaluatePath(doc, 'a.b') will now return 3
    and
evaluatePath(doc, 'a\\.b') will now return 2

Related to mrodrig/json-2-csv#184