Added SendTweet demo sketch for Twitter 1.1 API

Sends tweets directly from WiFi-enabled Arduino using new 1.1 API, no
proxy server required
Add sntp client

Added sntp clinet to utility folder, added ntpTest example sketch
Revert "Add sntp client"

This reverts commit 1229f8f2b78a21cf85309e0c797ec135dc4fe64d.
Add sntp client

Added sntp clinet to utility folder, added ntpTest example sketch
Added comments
Add month and weekday string tables; eliminate twelve_hour argument

Added month and day-of-week string tables to ntpTest example.
Got rid of unused "twelve_hour" argument to sntp constructors
Updated MAXLENGTHKEY
fastrprint
Add interrupt pin definitions for Teensy boards
Workaround for fd_set on ARM processors
More workarounds for C library conflicts on ARM
Add const to string pointers to constant data
Merge pull request #8 from PaulStoffregen/master

Support Teensy 3.0 & ARM, plus minor const pointer fix