Add step to rotate screen, fix issue with UIAlertViews in landscape.

The following method should provide hours of fun:

    [system
simulateDeviceRotationToOrientation:UIDeviceOrientationLandscapeLeft];

I used this to validate and fix issues #60 using the approach outlined
in that issue.
Fixed running test on iOS 5 from GM

Storyboard was targetting 6.1 as a minimum version. Lowered to 5.0.
Added test to validate that testFieldShouldReturn: is called when "return" is tapped.

Testing issue #216.
Update README.md

Removed temporary message about Cocoapods.
Removed references to KIF-next.
Updated images to point to kif-framework URL (avoid redirect).
Rework `UISearchBarTextField` first responder detection to support `UISearchBar` instances under iOS 7
Improve handling of search fields.

Search fields are hard to work with since their labels are nil.  This
implements two changes to simplify that.

1. Passing `nil` into *any* accessibility label parameter should work
if the element's `accessibilityLabel` is also `nil`.
2. Add `waitForFirstResponderWithAccessibilityLabel:traits:`

This way, search field text can be accessed with a
`nil/UIAccessibilityTraitSearchField` combo.

Related to issue #257.
Made scroll view and table view methods use accessibilityIdentifier rather than accessibilityLabel.

These views shouldn't really receive accessibility labels.  With iOS
5.0, they should be using accessibility identifiers.
Update README.md

Removed reference to inactive OSX port.  Added details about supported OS versions, supporting issue #96.
Readded writing screenshots when tests fail.

Resolves issue #247.
Add system test step to capture on demand screenshots.

Resolves issue #145.
Update README.md

Added note about `:exclusive => true`
Merge pull request #259 from kif-framework/better-handle-search-fields

Improve handling of search fields.
Merge pull request #258 from kif-framework/accessibility-identifier

Made scroll view and table view methods use accessibilityIdentifier
Select the view from the highest window.

Per #196, this code didn't make a lot of sense.  It would end up just
taking the view from the `windows[0]`.  Here we actually stop when we
have a viable view.
Mention correct environment variable.
Merge pull request #264 from plu/master

Mention correct environment variable.
Merge pull request #257 from blakewatters/bugfix/update-searchbar-support-for-ios7

Rework `UISearchBarTextField` first responder detection to support iOS 7
Added test for entering return character.

Checks for behavior described in issue #262.