Travis requires qt4-default to build
Include the overlapping xpath for ClickeFailed from obscured elements

This makes it easier to debug failed clicks because of modals, etc.

Example message:

    Failed to click element /html/body/div[@id='one'] because of overlapping
    element /html/body/div[@id='two'] at position 199, 199
Only require 'webrick/cookie' in order to avoid long load times on ruby 2.0.0-p195
Merge pull request #545 from pivotal-cloudplanner/master

Only require 'webrick/cookie' in order to avoid long load times on ruby 2.0.0-p195
Improve failure message when trying to click invisible elements

When not ignoring invisible elements, the message didn't explain that
the click failed because the element was invisible.
Bump selenium-webdriver

Closes #500
Don't bundle with deployment on Travis

Deployment mode breaks appraisals
upgrade rspec
remove warnings about un-initialised variables
switch from == to eq to remove warnings
remove warnings about variable shadowing
remove warning about ambiguous arguments
using stub to create test doubles is deprecated, use double directly
specifying an error not to raise is deprecated
stub! is deprecated and will be removed, use stub
fix spec that was wrongly passing before
fix typos
Add license to gemspec

Fixes #567.
Add integration coverage for styled file inputs

Uses example from Quirksmode:
http://www.quirksmode.org/dom/inputfile.html
Save a screenshot when raising a ClickFailed exception

* Prints the path to the file
* Make it easier to debug what was actually clicked