Selenium Infrastructure

Meant to open this yesterday. Creates a selenium test case with the following properties:

* self.browser - a selenium driver, currently PhantomJS (so no worries about running tests highjacking your display).
* self.find - alias for webdriver.find_element_by_name, find_element_by_id, and find_element_by_xpath

Examples:
```python
# find element with the id "foo"
foo = self.find("foo")
# find element with name "bar"
bar = self.find(name="bar")
```

I'm contemplating either using [splinter](http://splinter.cobrateam.info/) or writing a fascade to make selenium more pleasant to deal with. We may not bother writing enough selenium based tests for that to matter, so I'll hold off for now. It may also make sense to make the testcase a mixin instead of a standalone super-class.