Add SPI package to be installed too.
Update the libusb/libusbx versions
Remove useless `__del__` and `close` method from Generic 25 SPI flash device implementation
Merge pull request #20 from rogerhu/spi_extensions

Add SPI package to be installed too.
Move flash device support out of pyftdi
Move SPI device and JTAG arm out of pyftdi tree
Fix path in documentation file
Update version number
SPI flash device is not installed with PyFTI package,
as it is an example of use, but not a functional piece of the
PyFTDI package.
Do not hardcode URL within the README.rst file
Update JEDEC information for W25Q series.

0x4011 - 1Mb
0x4012 - 2 Mb
0x4013 - 4 Mb
0x4014 - 8 Mb
0x4015 - 16 Mb
0x4016 - 32 Mb
0x4017 - 64 Mb
0x4018 - 128 Mb