Add wokd startup options to enable/disable plugins

[Truja]

The idea is include new options to pass to wokd when starting it, regarding plugins initialization, like: "--enableplugins=<pluginA, pluginB, ...>" --> start Wok server only with those plugins "--disableplugins=<pluginA, pluginB, ...>" --> start Wok server without those plugins

Maybe: "--enableallplugins" --> enable all (could be replaced by '' in --enableplugins) "--disableallplugins" --> disable all (could be replaced by '' in --disableplugins)

These options would superimpose "enable" tag from plugins configuration files.

[alinefm]

Depends on #22