Update StaticAsset domain to include StorageType as either DATABASE or FILESYSTEM
Service changes to allow the system to store assets on the filesystem (in addition to the existing method of storing files in the database).

Introduced cms/common.properties to control the following whether or not the system should use the filesystem or the database, the maximum file size allowed,  the path where assets will be stored, and the buffer size used by input reading/writing operations.
Merge pull request #37 from BroadleafCommerce/file-based-assets

Provide ability to server Static Assets from the File System