Add a Gem version badge
Add a Gem version badge

This is a little preemptive since we're not on RubyGems yet.

frbl/active_interaction,orgsync/active_interaction,AaronLasseigne/active_interaction,AaronLasseigne/active_interaction,orgsync/active_interaction,antoinefinkelstein/active_interaction,antoinefinkelstein/active_interaction,frbl/active_interaction,JasOXIII/active_interaction,JasOXIII/active_interaction