Add a subclass of CallablesFilter that also implements the DependencyExtractor interface.

Useful for tests, among other things.
Fix totally screwed code >:-)

Better run once before push.
Fix return value if no extractor given
Merge DependencyExtractor callable into baseclass
Add a test for non-intuitive behaviour
Add a test
Coding standards
removed unnecessary executable bits from files
Merge pull request #434 from TravisCarden/master

Remove unnecessary executable bits
Merge pull request #431 from mpdude/callables-dependency-extractor

Add CallablesDependencyExtractor
Merge pull request #432 from mpdude/fix-string-asset-content

StringAsset's pre-canned content not available unless load()ed