Improve the test for change events when calling fill_in.

  - Assert that the event is triggered.
  - Assert that the value of the input is correct at the time the event
    is triggered.
  - Do not allow multiple events to be fired for a single change.
Specify :match => :one explicitly.
Add double_click and right_click to element - support in selenium
test for issue of cookie not getting set in rack test when first request has a blank path
Fix for issue with cookie setting on first request with blank path
Save page anyway if launchy is not installed
Updated README to make driver registration and configuration more clear.
fixes #1168
use double instead of mock to get rid of the deprecation warning
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Merge pull request #1171 from Gaelan/patch-1

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Merge pull request #1169 from gurix/issue-1168

fixes #1168
Merge pull request #1158 from rocketmobile/master

Updated README to make driver registration and configuration more clear.
Merge pull request #1142 from justincampbell/save-without-launchy

Save page anyway if launchy is not installed
Remove useless print statement
Move result creation into synchronize block, closes #1097
Improve resetting of page, closes #1035

Navigate to an empty HTML instead of navigating to about:blank. Hopefully this should work better than before.
Support filling in `contenteditable` elements, closes #911
Add `option` option when selecting radio buttons or checkboxes by their name, closes #1040
Make it clear that selenium requires a gem, closes #1075