Fix Debounce example to work as described

This alters the debounce example code to toggle the LED rather than just use
the button state to set the LED state.

Fixes #293
Added function on WString class to export char ptr
Added WiFi Udp Implementation
Fix bug on client.available() to retrun the number of bytes available
Updates to WiFi shield firmware.
Updated binaries for Wifi shield
Revert "Added function on WString class to export char ptr"

This reverts commit a0c96bebddac27e8ea51811a74d6cdfa2d8a30e0.
Merge remote-tracking branch 'arduino/master' into wifishield-bugfix
Added example WifiUdpSendReceiveString
changes in the script for upgrading the wifi shield
Merge branch 'wifishield-bugfix' of github.com:arduino/Arduino into wifishield-bugfix
Fixed issu con client.available to return the correct number of bytes
Fix problem on UDP NTP client
Add info instead of printk
Commit Binary
Fix issue related to multiple client opened on web server sketch
Merge remote-tracking branch 'mlafauci/wifishield-bugfix' into HEAD
Added API to set static IP and DNS server
Fix issue with multiple clients on WebServer
Backported malloc and realloc from avr-libc 1.8.0 (without test code)
See #857