Use labels rather than slugs when downloading files and in Solr

- Store the label property rather than the slug property in Solr
- Use the label property for a filename when sending a file, and change the method signature of the private version of streamData in FedoraContentService to use the term "filename" rather than slug
- Change FedoraProperty in ContentModelHelper to save the property's fragment as well as the entire URI
Use new StringFormatUtil.makeToken to set the filename param of the Content-Disposition header

- Move StringFormatUtilTest to access-common
Remove unused PathUtil
Fix regex quoting
Merge pull request #221 from UNC-Libraries/no-slugs

Use labels rather than slugs when downloading files and in Solr