Spark firmware v0.3.4

v0.3.4

FEATURES

• Local Build: Specify custom toolchain with GCC_PREFIX environment variable (firmware, core-common-lib, core-communication-lib)

ENHANCEMENTS

• Wiring: More efficient and reliable print(String) (fix issue #281) #305
• DFU: Add DFU suffix to .bin file #323

BUGFIXES

• I2C: Use I2C polling mode by default #322
• Listening Mode: Fix hard fault when Wi-Fi is off #320
• LED Interaction: Fix breathing blue that should be blinking green #315