Traffic cop the linux install process

This makes it so @iwebhub can support more linux distributions without much effort by just manipulating the new ```./script/setup.linux``` instead of making ```./script/bootstrap``` really long. This also means that ```./script/setup.apt``` is now located in ```./script/linux/setup.apt```.

I also adjust the system install check to a shorter block check for support on even more OS's in the future (BSD, Windows, etc). To support a new OS, issue the following command from the play root directory: ```filename="./script/setup.$(uname -s)" && touch $filename && chmod 0755 $filename && git add $filename```