added postinstall hook (#3303)
added postinstall hook (#3303)


switchinnovations/pxt,Microsoft/pxt,switch-education/pxt,playi/pxt,playi/pxt,switch-education/pxt,Microsoft/pxt,switchinnovations/pxt,Microsoft/pxt,playi/pxt,switch-education/pxt,switch-education/pxt,playi/pxt,switchinnovations/pxt,switch-education/pxt,switchinnovations/pxt,Microsoft/pxt,Microsoft/pxt