rework tools and make versions configurable

and change the version of riemann client/tools
smaller revisions

- add riemann-client::net
- revert changes to riemann-client::health
- make riemann-client::tools install riemann-tools gem only
search for attribute as last resort
add documentation and license
fix riemann/tools_version attribute use in nova/kvm
make monitors report the node's FQDN as event host