constrain reel-rack

On a fresh ruby installation.

ERROR:  While executing gem ... (Gem::ImpossibleDependenciesError)
    The user requires motherbrain (= 1.1.2) but it conflicted:
  Activated reel-0.4.0 instead of (>= 0.5.0) via:
    reel-rack-0.2.0, motherbrain-1.1.2
  Activated reel-0.4.0 instead of (>= 0.5.0) via:
    reel-rack-0.2.0, motherbrain-1.1.2