Added a config option for including content preview.

Often my content preview is someone tweet or something else I'm not interested in preserving.  This provides an easy way to include it or not.
Modified date format of dteToday as matching was not working.
Merge pull request #152 from dcwalker/master

Added 'instapaper_include_content_preview' config option
Merge pull request #153 from brs/things.2

Modified date format of dteToday as matching was not working.
Merge commit '4026d5f387c691737e3035009ec1c0ef99f6229a'