Removed huge chunks of start/stop code, and made sessions started by default.
Removed the play admin button.
Stripped out huge chunks of attend/unattend/start/stop code.
Fixed some issues shown by the test suite. Board is green again.
Added open/close session functionality, so admins can limit when people join sessions.
Wrote tests for open/close sessions.
Resolved conflict.
Merge pull request #198 from drewww/remove-signup

Remove signup