Test PreviewWidgetController's clear() in case where this.mediaUI is null.
Remove org.korsakow.domain.Audio.stop()
Merge pull request #7 from tarmstrong/test-preview-widget-controller-clear

PreviewWidgetController's clear() fails in case where this.mediaUI is not null (missing `stop()` method)
Added unit tests for KeywordLookupRule
Merge pull request #8 from dreisch/rule_tests

Added unit tests for KeywordLookupRule
Added tests for ExcludeKeywordsRule
Merge pull request #9 from dreisch/exclude_rule_test

Added tests for ExcludeKeywordsRule