parameterized mesosphere_installation.
remove some specs that doesn't describe some desired state of the server but recipe's detailed install actions.

I keep content assertions for configuration files because these are "desired state" of converged server.
changed to use service resource instead of log message inspection in mesosphere's serverspec because mesosphere supports service scripts.
In source serverspec, changed 'running mesos-master, mesos-slave' assertions so that it can verify mesos-master, mesos-slave can startup if properly configured.
upgrade vm memory.
reorder mesosphere suites
Merge pull request #11 from everpeace/refactor/simplify_serverspec

Simplify serverspec