refactor configuration

[HLWeil]

(Reopened PR #20 because of commit inconsistencies)

Setup a configuration for the arc which is split into two files:

• The global configuration is located at the arcCommander installation and its settings therefore apply to systemwide to all arcs. This file comes filled out when installing arcCommander.

• The local configuration is located inside each arc. Its settings apply only to the specific arc, shadowing the global configuration settings when set.

Per default, editing the configuration via the cli will affect only the local configuration and therefore only one arc, but retrieving the configuration will merge the global and the local settings:

Editing the configuration can be done in three ways:

• Using the set and unset commands in combination with the global and local flags allows straight-forward editing of specific settings
• Using the edit command will open a editor text prompt with the current configuration. The user can add, remove or preferably change values. When saving and closing this prompt the changes are applied to the configuration files. Per default, what the user sees and where the changes are applied works like specified above (seen in the image). Again, by global and local this can be more finetuned by the user
• Opening the configuration files and writing stuff into them

Additionally, some settings (like verbosity) can be given when running a command, altering the behaviour only of this specific process

[HLWeil]

Good stuff. Can you please also add the help output of the CLI tool to the global readme?

Updated in ed3e982