Fixes #1: Support # comments

The editor config file format uses these comments and is compatible with
python ConfigParser. Since this implementation duplicates ConfigParser
it is appropriate for # comments to be supported.

Also add comments to the example config file. They have no effect on the
output.

See http://editorconfig.org/#file-format-details
Fixes #2: Remove dart:io import

The ini.dart file now no longer has the 'dart:io' import, allowing it to
be used in the browser or on the server. The README has been updated
with code that does file operations itself.

I thought about keeping the file methods in derivative code but it
really adds very little. If a Config::Any style loader is written then
it will be useful for that to have access to the file name to determine
the loader. Until that point it does not matter.
Increase version
Merge branch 'release/1.0.0' into develop