* bug fixes
* Added CI: tests and auto release

Like all network operations, performing the POST request may fail for various
reasons. When no response from the remote end is received, a requests.post()
call may never return, leading to an unbounded increase in the sender queue.

To remedy such situations let's add a timeout argument to the requests call and
make it configurable, to be adaptable for different environments.

For more information see
https://2.python-requests.org/en/master/user/quickstart/#timeouts

If you pass an empty list, tuple, False, 0, whatever.. it will assume th
token is valid, which it isn't.

Currently the module raises generic Exception (very "don't do it")

Currently logging with:
```
logger.info('hello %s', 'world')
```
will send the string "hello %s" to logz.io instead of "hello world"

This commit fixes this situation.

Add tests

Allow custom logzio fields to top level structure