CRC class implementation

CRC class `MbedCRC.h` is templated class created to support hardware/software
CRCs. Default CRC will be hardware CRC when support for HAL is available.

Polynomial tables are available for 8/16 bit CCITT, 7/16 bit for SD card and
32-bit ANSI. Polynomial table implementation will be used if Hardware CRC is
not available.

In case device does not have hardware CRC and polynomial table is not supported,
CRC is still available and is computed runtime bit by bit for all data input.

Author: deepikabhavnani