servioticy plugin: timestamp should be in seconds not milli-seconds

According to http://docs.servioticy.com/ and http://www.servioticy.com/?page_id=106 the suggested format is seconds.
servioticy plugin: properly parse and escape data values using JSON API

Eg. strings need to be escaped with "", numbers don't need these.
servioticy plugin: fix up form denominations
servioticy plugin: remove some unneeded stuff
servioticy plugin: make host and port configurable

This allows to use custom ServIoTicy installations