Keep a label for each context.

[dashohoxha]

On the file config.sh we need to save a label as well. This is useful for the GUI case but also for the command line. The purpose of this label is to help the user distinguish clearly and easily one key from another (in a scenario when he may need to use more than one key). For example he may use one key for communicating with work colleagues, another one for communicating with friends, and a third one for communicating with family members. Each of these keys lives in a different context (homedir). Normally the user should be able to distinguish them from each-other by the key id (or fingerprint). However this is more difficult and error prone than distinguishing them by a simple and user friendly label.
Maybe we should also allow the user to switch easily the context of egpg from the GUI.