• Implemented PLATFORMIO_* environment variables (issue #102)
• Added support for SainSmart boards to atmelsam development
  platform
• Added Project Configuration option named envs_dir
• Disabled “prompts” automatically for Continuous Integration
  systems (issue #103)
• Fixed firmware uploading for atmelavr boards which work within
  usbtiny protocol
• Fixed uploading for Digispark board (issue #106)