Hello,
I got it why Toaster web interface was not importing layers. Reason is I have sourced wrong script file. Their are two script file in my distro/yocto one is for ls1012afrwy card's script which I usually source it while building any image related to it in terminal and another is oe-init-build-env in poky directory which is the correct script file to be sourced to make toaster to import layers.
Steps followed is:
cd ~/path-to-poky-dir
source oe-init-build-env build-with-toaster
source toaster start
Go to http://localhost:8000 and can import layers now
Here build-with-toaster is a directory which will be created to store toaster info