Release 2.0.0

Summary:

This release adds support for several new plugins and contains
some backwards-incompatible code refactors.

Backwards-incompatible changes:

- Storerates=true is now the default for the Graphite plugin
- Deprecate write_network plugin, use network plugin instead
- Make sure plugin configs are not world readable.
- Handle plugin order with collectd::plugin resource type
  (all collectd plugins config files will be renumbered from
   00-$name.conf to 10-$name.conf)

Features:

- New plugins CSV, uptime, users, entropy, varnish, redis,
  contextswitch, cpu, nfs, vmem, libvirt
- Add socket parameter to mysql plugin
- Add reportbytes to swap plugin
- Add SeparateInstances setting to write_graphite plugin
- Add metadata.json for Forge search support

Bugs:

- Fix port parameter quotes in memcached plugin
- Fix collectd conf dir path parameter assignment
- Fix processes plugin configuration
- Force ReportReserved to true in df plugin