Add /usr/sfw/bin to the solaris path

This is because on Solaris, wget is available in the non-standard path
/usr/sfw/bin as a last resort.
extract: add support for .tar.bz2 files

fix syntax error

fix syntax error
extract: add test for .tar.bz2 files
Merge pull request #21 from reidmv/solaris_support

Add /usr/sfw/bin to the solaris path
Merge pull request #22 from gizero/extract-tar-bz2

Add support for .tar.bz2 archives to extract