title: sbt submit gives "not a valid command" error
body: <p>Trying to submit my assignments. Looks easy from the demo, but receiving weird error. SBT version is correct. What may be wrong?</p>
  
  <pre><code>&gt; sbt-version
  [info] 0.12.4
  &gt; submit
  [error] Not a valid command: submit (similar: set)
  [error] Expected '/'
  [error] Expected ':'
  [error] Not a valid key: submit
  </code></pre>