Fix help for flash to not include invalid combinations
Fix help for flash to not include invalid combinations

Fixes #115

spark/particle-cli,spark/particle-cli,spark/particle-cli,kennethlimcp/particle-cli,kennethlimcp/particle-cli,spark/particle-cli,kennethlimcp/particle-cli,kennethlimcp/particle-cli,spark/particle-cli,kennethlimcp/particle-cli,kennethlimcp/particle-cli,spark/particle-cli