Implement a custom HystrixPropertiesStrategy plugin

Add a custom HystrixPropertiesStrategy implementation where getCommandPropertiesCacheKey is overridden to return null so that HystrixPropertiesFactory will always generate a new HystrixCommandProperties for each new HystrixCommand instantiation.
Not sure if it was the way we were using it, but `coveralls` task is troublesome in that if the compilation fails ([like this](https://travis-ci.org/m3dev/octoparts/builds/36740208)), the exit status is 0 and the whole build is marked as successful :laughing: 

There may be a more elegant solution to adding `test` after `coveralls` but I'm not too sure.