'mk' commands stores meta info
'ls' commands able to read meta info; fixed tests
update CHANGELOG
impoved autocomplete for commands 'mk'/'ls-versions'
update CHANGELOG
improved go-plugin
added python plugin
update README
update README
added plug_add_activate_script function for plugins
small fix in all plugins
added call 'deactivate-' scripts during 'off'/'deactivate' commands
fixed go plugin: restore old values of the GOROOT/GOPATH during deactivation
new test for go plugin: restore old values of the GOROOT/GOPATH
command 'rm-envs': output message if environment was successfully deleted
'ls-envs': added environments sorting
fixed go plugin: improved activate-go to be usabale after copy
renamed ls-envs to ls
added test to check correct paths after copy env with activate-* script
rm-envs renamed to rm