skeletal plugin files
configuration reading/parsing and installation of triggers and hooks
* GO_Sync_User_Map class and related unit tests.
* refactored out the setUp(), tearDown() and clear_caches() functions into an abstract test class.
clean up the go_syncuser singleton between tests so a clean config file can be added
added cron-related functions
better check for empty cronned users list
removed the field mapping-related functions which should go into the dependent plugins
* use a better name for the cronned user meta key
* use sanitize_user() to normalize the user argument in the action hooks, which obsoletes the "user_token" field in the trigger configurations
* make all class member vars private
* fixed an erroneous reference to go_mcsync
* coding standard fix (too many spaces inside braces)
* added default configuration
* moved "batch_size" and "is_cli" to the config file
removed the "is_cli" config entry and just is php_sapi_name() to check it.
Merge pull request #1 from wluo/go-syncuser

the go-syncuser plugin