Ignoring IDEA files
Added Spock Test Framework
Added Integration test For AssetHelper.
Added test for getting an asset that doesn't exist.
Added integration test for retrieving CSS file.
Refactored AssetHelper.

Extracted a function from fileForUri to make it a little more readable.
Extracted another method from AssetHelper.fileForUri
Using Appache Commons to copy files.

http://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/FileUtils.html#copyFile(java.io.File, java.io.File)
Revert "Using Appache Commons to copy files."

This reverts commit 564081473cfd19af71c84765562fe55ccaf2b2e3.
Moved test asset files to an asset-pipeline dir.

So it doesn't interfere with other plugins.
Merge pull request #4 from uris77/asset-helper-test

Asset helper test
cleaned up assets and added a new integration test
continuous integration
fixing readme
oh travis
added build status badge
correcting bug in recursive tree append
correcting bug in recursive tree append