Updated listfiles SD example

Updated description of the file
Updated Blink without delay example

Changed variable to unsigned long.
Modified LCD custom character example

moved lcd.begin() to the beginnng of the setup() and fixed an issue
that prevented the example from compiling. When calling lcd.write()
with an argument of 0, the 0 must be cast a s a byte.
Updated KeyboardMessage example
Fix SERIAL_* metadata in Arduino Ethernet variant
Merge remote-tracking branch 'arduino/master'