New description field

[Sriep]

Add a new description field to 0chain.blober.yaml. Pass this to blobber when joining a 0chain network with add_blobber.

Works with 0chain/0chain#938.

[Sriep]

Check here for further details here 0chain/0chain#921. We want a name, logo description and reference link.

[moldis]

#606