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.
Save page anyway if launchy is not installed
Updated README to make driver registration and configuration more clear.
WEBrick has to bind proper host specified in `Capybara.server_host`
Results can now be sampled.

An instance of Result can now call #sample. This is delegated to Array#sample.
This allows a random result to be chosen.
This is useful if we want to check one of the results but with no particular preference as to which result.
Merge pull request #1161 from route/fix_server_host

Make `Capybara.server_host` working properly
Merge pull request #1162 from asmega/result_sample

Results can now be sampled.
fixes #1168
use double instead of mock to get rid of the deprecation warning
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Document project license in gemspec
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