Add SensorNode and SensorNodeV2 supports

Main change:

+ Add CooCox CoIDE project files;
+ Add sim39ea diver;
+ Add hardware testing examples, FSKTx(transmit continuous wave), LoRaTx, LoRaRx;

SensorNodeV2 contains no external 12MHz oscillator, so system_stm32l1xx.c is edited to enable HSI of STM32L151xxx as PLL clock input.