Overwrite and list co-author initials

Added

• Overwrite the main author using git mob -o <initials> see example. Thanks to @eric-thelin and @Sarabadu
• Add initials of current mob to PS1, in ~/.bashrc see example Thanks to @joelash
• Minor improvements to readme documentation

Fixed

• Update dependencies to patch security alerts

Major release of Git Mob because commands have been stable for a while and there a no immediate plans to introduce breaking changes.