Full rewrite of the network plugin

It now allows more than one server and more than one listener. It can be
configured both by parameterized class and by invoking defined types
collectd::plugin::network::server or collectd::plugin::network::listener
Rewrite of postgresql module to allow invocation by defined types

It now also support defining custom queries.

As a bonus, this rewrite is backward compatible (!)
Merge pull request #168 from txaj/postgresql-module-rewrite

Rewrite of postgresql module to allow invocation by defined types
Merge pull request #165 from txaj/extend-network-plugin

Full rewrite of the network plugin
Issue 164: syslog plugin needs to be loaded as first plugin

If the syslog plugin is not initialized as first plugin, other plugins
won't be able to log their startup/fail output at load time.

reported by bzed
Merge pull request #166 from txaj/syslog-loaded-first

Issue 164: syslog plugin needs to be loaded as first plugin
Add the possibility to customize package name.

For example, this add the possibility to install 'collectd-core' instead
'collectd'. Less dependencies and enough to make the collector work on
clients.
Merge pull request #170 from bdossantos/feature/custom_package_name

Add the possibility to customize package name.