Adding ``smoke`` tests to our Docs.

Realized that our docs did not mention the new ``smoke`` test suites.
Merge pull request #1105 from omaciel/add-smoke-to-docs

Adding ``smoke`` tests to our Docs.
Added ``Ping`` test to API smoke suite.
Fixing code indentation as per Jeremy Audet.
Cleaner list comprehension as per suggestion.
Merge pull request #1104 from omaciel/can-haz-ping

Added ``Ping`` test to API smoke suite.
Flesh out the ComputeResource entity

When creating a new "compute resource" entity, a variable set of values must be
provided to the Foreman server. The exact set of values depends on the specified
provider. (e.g. EC2, Rackspace, etc.) Flesh out the ComputeResource entity with
logic necessary for handling this variability in requirements.
Add some API tests for the ComputeResource entity

All tests for the ComputeResource currently fail. These tests fail for a variety
of reasons. For example:

* Creating a compute resource with a provider of 'Rackspace' causes Foreman to
  throw an HTTP 500 with the message "undefined method `upcase' for
  nil:NilClass".
* Creating a compute resource with a provider of 'GCE' fails because Foreman
  needs more data. However, the types of data needed are not discussed in the
  API docs.
* Creating a compute resource with several other providers causes Foreman to
  return the following error: "getaddrinfo: Name or service not known".

These issues should be tackled by someone who knows a bit more about how compute
resources work.