Multiple improvements

Alright, I added a *auto_build_local* target which builds from the local_feed dir without changing any branches.

Also added is that with the development release pbxopkg and piratebox-mesh are pulled and build from their package repos instead of wgetting them. (*auto_build_development*) Therefore I also added a OpenWRT config for the development target, enabling pbxopkg and piratebox-mesh.

I also took the time to test building the following targets and installing it on my MR3020 each after flashing the original TP firmware first to ensure that each of the targets produces a working result.
* auto_build_stable
* auto_build_beta
* auto_build_development

I will update the Readme now accordingly.