update changes to reflect 0.44.7 release
update changes to reflect 0.45.1 release
load crate modules using ServiceLoader instead of es plugin mechanism

also add fatjar plugin to be able to create a single crate
jar.

The es-plugin mechanism doesn't work with a single jar file
as there can only be one es-plugin.properties file and that
can only have one "plugin" key.

In order to work around that the CrateCorePlugin is now the
only plugin loaded using the es-plugin mechanism and that
plugin is loading all other crate components (using the stock
java ServiceLoader which works using META-INF/services files
which can be merged in a single jar file)