Sample using vSphere PerfMgr API

Originally contributed by @lamw some additional clean up makes the sample conform to project standards.
Merge pull request #6 from hartsock/esxi_perf_sample

Sample using vSphere PerfMgr API
A collection of samples contributed by
@mjbrender

 * commits have been crushed down to one transaction
 * files have been renamed
Sample cleanup and bug fixing.

* introduces cli.py and vm.py for sample utilities
* moves packages to more useful locations
* fixes minor bugs found through manual testing of all samples
* fixes pep8 errors found through pep8 testing
Merge pull request #10 from vmware/pr/7

samples: create_random_marvel_vms, esxi_perf_sample, getallvms, hello_world_vcenter, vcenter_details