Temporarily removed CRC checking

HTU21D/HTU21D.cpp: In function 'float readHumidity()':
HTU21D/HTU21D.cpp:49:20: error: 'checkCRC' was not declared in this
scope
if(checkCRC(h, crc) != 0) return(999);
^
HTU21D/HTU21D.cpp: In function 'float readTemperature()':
HTU21D/HTU21D.cpp:85:21: error: 'checkCRC' was not declared in this
scope
if( checkCRC(t, crc) != 0) return(999);
^
make: *** [HTU21D/HTU21D.o] Error 1