Update valid_connect.xml Fixture for Escaped XML

Update the valid_connect.xml fixture file to ensure that it contains
escaped XML (well-formatted XML).
Add all_hosts Spec and Fixture for Server

Add specs to test the Server all_hosts instance method, along with an
all_hosts.xml file that contains examples for a listing of all
respective hosts and their corresponding monitors.
Add hosts Spec for Api

Update the Api spec to include tests for the hosts method.
Update Version11 Class for hosts and host_path

Update the Version11 class to include the hosts method and host_path.
Add all_hosts to Server

Update the Server class to include the all_hosts method to return a
listing of hosts and arrays of their respective services being
monitored.