Improve the freebsd parser in the packagedcode

There would be two things we can improve.
1. parse function in freebsd module can accept the file content besides the file location, which means it can support two kinds of the paras, current file location and the file content, in that way, if there is a file content string, there is no need to save the content into a temp file and then pass into the function.
2. The WWW is effectively part of the description and this is redundant but that's the way the FreeBSD manifest are set. The refinement could be to strip this out from the description on the scancode parser side if this is already properly returned in the "www" attribute of the FreeBSD manifest