adding overlay wrapper for interactive experiments

This makes simple experiments in an interactive python shell much
easier. After authenticating to a vCenter host interactively, it
is possible to directly iterate over all VMs with very little code.

Wrappers are provided for convenience, though they passthrough any
undefined fields or methods to the underlying VIM object.
fix import order. fixes issue #94
Merge pull request #95 from michaelrice/issue_94

fix import order. fixes issue #94
Merge pull request #93 from mriehl/sample/simple-interaction

adding overlay wrapper for interactive experiments
Fix esxi_perf_sample variable names
Fix travis build and URL in setup.py
Merge pull request #99 from LeoCavaille/fix_travis_build

Fix travis build and URL in setup.py
Merge pull request #98 from LeoCavaille/master

Fix esxi_perf_sample variable names
.travis.yml - Remove Python 3.x 

We won't be ready to officially support Python 3.x in the samples until after we release a version of pyVmomi with official Python 3.x support.
README.md - add travis-ci build badge

Adding travis-ci build badge to public README.
Update setup.py - point to gh-pages

Point the setup.py to the http://vmware.github.io/pyvmomi-community-samples/ site instead of the github repo.