Use rabbitmqctl wait for rabbitmq container startup

[jerith]

Fixes #88.

[codecov[bot]]

Codecov Report

Merging #92 into develop will decrease coverage by 0.07%. The diff coverage is 60%.

@@             Coverage Diff             @@
##           develop      #92      +/-   ##
===========================================
- Coverage      100%   99.92%   -0.08%     
===========================================
  Files           31       31              
  Lines         2593     2597       +4     
  Branches       163      164       +1     
===========================================
+ Hits          2593     2595       +2     
- Misses           0        1       +1     
- Partials         0        1       +1

Impacted Files	Coverage Δ
seaworthy/containers/rabbitmq.py	95.45% <60%> (-4.55%)	:arrow_down:

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[bearnard]

👍