=====October 31, 2016=====
  * change xbee debug lights to xbee voltage and gnd

=====October 20, 2016=====
  * change charging chip package
  * keep 2 boards stack
  * do solar irradiance sensor research
  * add gps module
  * <del> fix debug lights </del> MCU debug lights can be programmed in the code
  * add more test points - SCL, SDA, xbee voltage, etc
  * make board slightly bigger