Sample apps for configuring LLDP using OpenConfig

[deom]

This is my first commit to the ydk-py samples!

I have added the following CRUD sample apps for OpenConfig LLDP. 

nc-create-config-lldp-10-ydk.py - create boilerplate
nc-create-config-lldp-20-ydk.py - enable LLDP
nc-create-config-lldp-22-ydk.py - enable LLDP with timer
nc-create-config-lldp-24-ydk.py - enable LLDP with TLV adv
nc-delete-config-lldp-10-ydk.py - delete boilerplate
nc-delete-config-lldp-20-ydk.py - delete all LLDP config
nc-read-config-lldp-10-ydk.py   - read boilerplate
nc-update-config-lldp-10-ydk.py - update boilerplate

You can see the entire basic CRUD/LLDP OpenConfig sample apps in this page:

https://github.com/CiscoDevNet/ydk-py-samples/tree/master/samples/basic/crud/models/openconfig/openconfig-lldp

Have Fun!