v0.2.3 features and fixes

-v --version support
-l --list option for listing available projects and contexts
-l can receive either p (project) or c (context), as well as an optional :filter on the argument (e.g. '-l c:email' shows all contexts containing a fuzzy match of 'email')
-c switch can be used with the -l flag to output space-separated lists for use with shell completion
Better project/context fetching features, ignore unavailable
improved fuzzy match project/context name results
Updated readme for 0.2.3