latest changes pushed to production

[Murali Dharan]

Hello all,

Changelog for latest push to master branch.

* multiple atsign support in at_client SDK. App developers can now leverage this feature to enable users to authenticate any atsign owned by them in a single app.
* batch verb to improve sync performance. During sync, multiple update/delete commands will be batched and sent over  to the server thus reducing the number of network calls.
* minor bug fixes

Below packages have been published to pub.dev
* at_lookup 1.0.0+4
* at_client 1.0.1+4
* at_client_mobile 1.0.0+4

Thanks,
Murali