multi-tenancy support and minor features/improvements

I've made a number of changes based on @mantree fork

- internal metrics are now generated and sent through internal channels
- channel sizes and batch sizes fore ES REST interface and cassandra store can be configured 
- multi-tenancy support 
- debian package will behave differently, namely it will not create metric store on 'localhost' by default as in most cases cassandra will not listen on localhost. Also some meaningful defaults to JVM were added