Use with eventmachine 1.0.0

In order to avoid gcc errors in debian wheezy, event machine must be >= 1.0.0. I changed the code (not a lot ;) ) in order to make it work (no tests done but it's working without any issue for two days on my raspberry pi)

Bump version of eventmachine to "1.0.0"
Update lib/em-serialport.rb to make it work with eventmachine > 0.12.10 in pure ruby mode
Update version number