Introduce new command that read/tail error/info log

Possible read commands:

• leprechaun error-log
• leprechaun info-log

Possible tail commands:

• leprechaun tail-error-log
• leprechaun tail-info-log

These commands will try to read global error and info logs if they are specified as global. Every service can have it's own error and info log so we should include default commands in age

With Gnome NetworkManager one can set, wheter a connection is metered (other word for metered is "fee-based").
On a metered connection, smart programs will stop unimportant background activities such as system updates, backup jobs and so on.

It comes handy to set the property to yes in situations like a capped data plan or on a generally slow WiFi connection.

Borg-cron-helper should