Gw2pvo

Sems APV v1 seems to be deprecated, it's certificate has not been renewed. For more details, read 42.

Fixes [the first value for the day is too high](https://github.com/markruys/gw2pvo/issues/16).

Added a check on Python 3 during installation, plus removed some dependency on Python 3.5.

As GoodWe phased out the old API, the application was rewritten to use the GoodWe Sems portal.

Note that you now need to add your GoodWe username and password to the invocation of the script.

Added the option `--gw-region` to set the region. Also switched all communications to https.

First release