Only install gradle if it is not already installed
Only install gradle if it is not already installed

Otherwise, the `sdk install gradle` command returns with an error that causes
the script to terminate

shankari/e-mission-phone,e-mission/e-mission-phone,shankari/e-mission-phone,shankari/e-mission-phone,shankari/e-mission-phone,e-mission/e-mission-phone,e-mission/e-mission-phone,e-mission/e-mission-phone