* Improvements in EspClass

- fixed not working functions for flash chip size, speed and mode
- added function to retrieve chip revision from eFuse
- flashRead / flashWrite supports encrypted flash

* Rename getCpuRevision function to getChipRevision

* Revert: flashRead / flashWrite supports encrypted flash

Reading and writing to encrypted flash has to be aligned to 16-bytes. Also NAND way of writing (i.e. flipping 1s to 0s) will not work with spi_flash_write_encrypted. Note: spi_flash_read_encrypted will always try to decrypt data, even if it wasn't encrypted in the first place.