Revert compile script changes, restore submodule

[neelabhg]

Some unintentional changes were introduced when #109 was merged (see https://github.com/s-macke/jor1k/pull/109#issuecomment-159967040).

This commit reverts commit cb30ffcc97b33b9bb58157a3c0a269139ac9add4 ("Merge pull request cmercur2/jor1k#2 from jjang16/master"), reversing changes made to 45cedeee46c5e5b4cd551bea3afafbfca7e72811 ("adding rename to filesystem").

In particular:

• The compile script outputs into the demos folder again (instead of bin/)
• The compile script does not create the "sys" symlink anymore
• The "sys" submodule has been restored

[s-macke]

Thanks