Add basic contributor guideline pointing to HQ URL

For the GitHub API https://github.com/blog/1184-contributing-guidelines

Signed-off-by: Simon Stewart <simon.m.stewart@gmail.com>
Unifying use of hamcrest matcher methods
Unifying use of waiting conditions
ENABLE_PERSISTENT_HOVERING moved to InternetExplorerDriver because it's
IE-specific capability
Sorting out some generics-related warnings
phantomjs is purely synthetic events
Use Markdown for rb/README.
ignore timestamp part of date (or any extra cruft sent)
fixing expectations for non-webkit browsers for date inputs
Updating logic in IE driver to correctly wait for the document.

Fixes issue #5326.
Adding ability to get current URL from IWebBrowser2 if IHTMLDocument2
fails.

Under normal circumstances, the IE driver gets the current URL from the
document loaded in the browser. When IE browses to a non-HTML page, such
as a PDF file with the Adobe Reader plugin installed, getting the document
fails, since there is no "document" in the browser. In that case, fall
back to getting the LocationURL property of the IWebBrowser2 interface.
It's arguable that this is the wrong thing to do, since the driver is
useless without an actual document, but we'll let this work anyway. Fixes
issue #5361.
Updating IEDriverServer prebuilts
WebDriver-backed Selenium tries to emulate Selenium Core's alert handling by
overriding the global alert functions in JS. This means any saved alerts
would be lost whenever a new page is loaded. Allow users to disable this
bit of functionality with a capability so they may test alerts using the
WebDriver API.
Merge branch 'master' of https://code.google.com/p/selenium