Fix file logging sample code.

Incorrect defaults configuration key, was 'defaults', should be 'config_defaults'.
Tested with cement 2.2.x on python 2.7 .
Fix duplicate pre_argument_parsing heading
Bumping version to 2.2.1 dev
Update ext_plugin.py

If a .conf file exists in the config_dir and it's first section has an enable_plugin key and enable_plugin is not true, the plugin name should be appended to _disabled_plugins, not the last section name from the early section scan (e.g. "log").

Copy-paste error, methinks.
Merge pull request #245 from delitescere/stable/2.2.x

Bug fix ext_plugin.py
Resolved Issue #243
Resolves Issue #241 and #242
Resolves Issue #237
Resolves Issue #234
Resolved merge
Resolves PEP 8 Issues
Resolves Issue #235 and #246
Fixes ChangeLog after merge from 2.3.x
Fixes PEP8 issues
Resolves test failures
Bumping version to 2.2.2