DD-WRT build svn revision 12357M

This is a build for DD-WRT svn rev no. 12357M.
It contains fixes to allow upgrading a chk file from GUI interface of DD-WRT.
It has been tested by upgrading default netgear chk file from GUI interface of DD-WRT and vice versa.
Others firmwares can also be uploaded provided they are build in proper chk format.
Also uploading this chk from GUI of other 3rd party firmware depends on the chk upgradtion support provided in those 3rd party firmwares.
As far as switching between default netgear chk and dd-wrt chk is concerned , it can be done without the need of any bin file upgradation in intermediate stages.