Rely on -user for lfe shell

Use -user lfe_boot instead of -noshell and -noinput.

This allows stdio functions to still work with lfe
since input is still available. -noshell and -noinput
now can also be given by the developer in case he
wants to disable one or the other.
Merge pull request #19 from josevalim/patch-1

Rely on -user for lfe shell