* * osimage table schema change: add a "environvar" col in osimage table to hold environment variables used in osimage customized files
* osimage object schema change: add a environvar attribute, which refers to osimage.environvar
* the environment variables specified in "environvar" attribute will be exported during invocation of postinstall scripts in genimage
* support variables in synclists
* support environment variables in genimage,mkinstall,getpostscript
* support environment variables for xdcp -i -F in packimage