WebDriverFactory is an interface
refactoring WebDriverFactoryLocal#getWebDriver

replacing the dumb switch/case with a Class#newInstance
add SupportedBrowser#toFullyQualifiedClassName
add SupportedBrowser#toClass
add WebDriverFactory#getWebDriver(SupportedBrowser)

which allows creating WebDriver regardless of the config property "tinafw.browser"
add User#equals
update User: the currently visited page is now part of the state of the object

- rm doTask(Page, WebTask)
- add field currentPage
fix/update javadoc
add unit tests

- User
- Browser
- WebDriverFactoryLocal
- SupportedBrowser
(tiny) update CompositeWebTask
change Browser#open: don't throw exception if browser was already open

We need that because in WebTest#testBody we need to be able to call
User#openBrowser as many times as we want.
fix sample due to UI changes to SearchResultsPage
fix log msg in PageHelper#browseTo
change LoadablePage and Browser#startSession

- Browser#startSession: rename to Browser#browseTo
- LoadablePage#getLoadablePage: change signature: take a WebDriver instead of a Browser