Added two sound modes found in android app.

-Added sound modes for 3 and 4

Added Ezviz CAS server functions and mqtt support for push messages.

-Can now enable/disable camera status again. (Binary request to Ezviz CAS server, encrypted with AES and xored serial)
-Added MQTT function for push messages.
(Just create ezviz user with password ezviz on your mqtt broker)
-Refactored code.
*Moved exceptions to seperate file.
*Moved some of the duplicated constants to constants file.
-Updated requirements file.

Fix for some cameras returning 0.0.0.0 ip.

-Fix for some cameras returning 0.0.0.0 ip.
-Also added android generic user agent for other OS types. (Windows IE gets different json formatted data as an example. Might be other cases as well)

Now raises library specific exceptions.

-Added specific exception for invalid urls.

Change default value to none if camera doesn't support defense schedules.

Change default value to none if camera doesn't support defense schedules.

Fixed arg parser for camera status.

-Fixed arg parser for camera status.
-Added method for defence schedule check. This isn't present on all cameras and resulted in errors.
-Small changes to public/private methods (Basically added _ to private methods as per PEP standard)

Now makes use of refresh token api

-Added refresh token support.
-Added Account credentials error messages. (on incorrect username or password)

Changed to pure API login.

Looks like ezviz is enforcing a captcha code. Was planning on moving to pure api login.

-Disabling/enabling of "defence" per camera doesn't work on this release yet.
-Can disable/enable on all cameras though via the switch_defence_mode api.

Added new module that tests RTSP camera credentials.

-Added new module that tests RTSP camera credentials. I'm planning on incorporating it on the Hass camera integration workflow.

Can now specify api URI for your region.

-Checks correct API uri for non isolated regions with the default. (basically everything on the .ezvizlife.com domain)
-Fixed a few spelling and typos.
-Improved a few error messages.
-Added local ip to constants for HA sensor.