I am finally able to hibernate from my primary OS (windows 7) and boot into secondary os (Linux Mint 15) and vice versa.

Steps required to do this setup:

1. Do a complete format and install Linux Mint ( or any other OS using GRUB2 boot loader)
2. Don't create a seperate partition to install boot loader. Select the Primary Disk sda for this.
3. You can boot into linux mint now. Do a clean shutdown.
4. Install Windows 7 in any of the partitions after Linux Mint swap partition
5. reboot. You won't be able to boot into linux now as Windows Boot manager disabled GRUB2.
6. After booting into Windows 7, install EasyBCD and add an entry for Linux Mint in the boot menu.
7. Restart and boot into Linux Mint from a live DVD/usb.
8. assuming the root partition of linux mint is sda1, mount it using the following command in terminal:

sudo mount /dev/sda1 /mnt
9. Reinstall GRUB2 as primary bootloader with the following command:
sudo grub-install --root-directory=/mnt/ /dev/sda
10. Reboot. You should be able to boot into Linux Mint now.
11. Run the following in terminal to update GRUB2 to include the bootloader of Windows 7:

sudo update-grub
12. now you can dual hibernate