Improve application and platform configuration

- we now have 3 layers:
1/ base layer. It simply registers the node in the logical cluster,
and monitors application configuration for the cluster
2/ platform layer. Based on the application configuration, it loads custom defined
modules, fetching them if necessary, then starts a Server with distributed app loader,
or starts an app directly
3/ app layer. Loads app code, fetching it remotely if necessary, and starts the app

- these layers use a hierarchy of classloaders (loading from modules jars and app S4R)
and of Guice injectors

- also fixed -clean parameter in zkServer tool (with arity of 0, specifying -clean means
cleaning, not specifying it means not cleaning)
Improve application and platform configuration
- added missing files
Fixed module loader tests + code that should not have been commented
S4-59 fixed s4-tools commands with new configuration scheme
- also fixed some parameters names that needed an update + doc
S4-59 use -clean=false as default for zkServer command
(since arity is 0)
Merge branch 'S4-59' into dev
- includes a few manual fixes for the merge