Fix Layout#getViews for unrecognized selectors

Return an empty array when no views exist at the specified selector.
Fixes GitHub issue #325.
Optimize Layout#getViews

Defer generation of comprehensive views collection until it is needed.
Optimize Layout#getViews further

`_.where` always returns an array, so there is no need to wrap the
result in an array and immediately flatten it.
Optimize Layout#getViews still further

Avoid "unchaining" the comprehensive views collection, and use the
chained version to calculate the correct result.
Merge pull request #326 from jugglinmike/optimize-getviews

Optimize Layout#getViews
Merge pull request #327 from jugglinmike/325-get-unknown-views

Fix Layout#getViews for unrecognized selectors
Correct cleanViews invocation of cleanup methods

Ensure that cleanViews invokes cleanup methods in the context of the
target layout.
Merge pull request #329 from jugglinmike/328-cleanup-invocation

Correct cleanViews invocation of cleanup methods
fix for travisci icon
Remove invalid test

`Layout.configure` does not support the signature exercised by this
test. The test only passes because it is using an invalid signature--the
functionality implied by the test is not supported. This means that
correcting the invocation results in a failing test, so the test should
be thrown out.
Merge pull request #330 from jugglinmike/configure-test

Remove invalid test