Error on AirLift/WINC1500 for Non-SAMD Boards

[brentru]

Scope

• Limit AirLift and WINC1500 classes to SAMD, AVR targets do not have enough memory to compile. This library previously limited WINC1500 to ARCH_SAMD, this PR will add it for AirLift.
• Add a verbose #error to avoid generic 'AdafruitIO_WINC1500' does not name a type typedef AdafruitIO_WINC1500 AdafruitIO_WiFi; errors when attempting to compile WINC1500 or AirLift with an AVR board.

Minor Fixes

• Update library.properties to mention airlift
• Update readme to mention airlift
• Bump version in library.properties and _definitions

Adafruit Support Forum post re:this issue: https://forums.adafruit.com/viewtopic.php?f=56&t=151221&p=748235#p748235

Sketch uses 34678 bytes (107%) of program storage space. Maximum is 32256 bytes.

Global variables use 1687 bytes (82%) of dynamic memory, leaving 361 bytes for local variables. Maximum is 2048 bytes.
Sketch too big; see http://www.arduino.cc/en/Guide/Troubleshooting#size for tips on reducing it.
Error compiling for board Adafruit Metro.

[brentru]

Closing in favor of https://github.com/adafruit/Adafruit_IO_Arduino/pull/89