minor doc fixes
add dump log message
export anyconfig.api.{container, logging, set_loglevel}
fix a syntax error that trailing ',' was missing
only allow kwargs for *ConfigParser.{load*,dump*}
[ini backend] pass optional arguments to configparser.SafeConfigParser{,readfp} if passed in load*
add an utility function mk_opt_args to process kwargs passed to load*/dump* methods and only pass valid kwargs to backend's load*/dump* methods
[ini backend] pass optional kwargs w/ using anyconfig.backend.base.mk_opt_args (but not enabled yet in actual)
[json backend] pass optional kwargs w/ using anyconfig.backend.base.mk_opt_args, and add some test cases
[yaml backend] pass optional kwargs w/ using anyconfig.backend.base.mk_opt_args, and add some test cases
[properties backend] follow internal API changes in base class
[ini backend] allow configparser specific options passed to load*/dump* methods
[ini backend] add test cases if configparser specific options passed to load*/dump* methods
allow backend specific options passed to [{single,multi}_]load*/dump* APIs, and add some tests for such cases
update the changelog entry for the next 0.0.3.9 release