CHANGE-561 lhungil github pull request - Installer Improvements. V160 use defined paths during install

commit: initial commit
Updated to use zcConfigureFileReader.
Updated to use DIR_FS_LOGS, DIR_FS_SQL_CACHE, and DIR_FS_DOWNLOAD_PUBLIC if defined in localConfig.php or the existing store's configuration file.
Will display the actual log, cache, and public folders locations in error messages if not found. Added TEXT_DB_VERSION_NOT_FOUND referenced by systemChecks.yml
Updated the systemChecks to use the constants DIR_FS_LOGS, DIR_FS_SQL_CACHE, and DIR_FS_DOWNLOAD_PUBLIC.
Removed hardcoded references to 'logs' folder in favor of using DEBUG_LOG_FOLDER.
Updated entrophy generation to always use a file known to exist during installation.
Merge pull request #20 from zencart/v160

CHANGE-561 lhungil github pull request - Installer Improvements. V160 us...