Store blobs to PROGMEM and define PROGMEM-compatible APIs

[dogtopus]

In order to provide better support for AVR Arduino boards, it would be necessary to store constant blobs to program memory in order to save RAM space. Since AVR does not map the program memory and the RAM to the same address space, it would be necessary to define APIs for anything that will potentially access the program memory (e.g. data transmit routine for transport class, etc.) and use them when appropriate.