Fixes debian installer for Raspbian Buster (see #324) by removing strict package dependency to package libttspico-utils.
Updated recommendation for Java 8 Runtime. Zulu 8 JDK is recommended now as it provides performant packages for all platforms and does not require a login as Oracle.
added license file to debian package and also added license inline.
updated some debian meta-information fields.
updated documentation about installer creation for all platforms.
libttspico-utils.