Added support for MAC OS X

wash now also works on MAC OS X
`wget`-binaries are not included in MAC, using `curl` instead.
octal display `od` (url encoding) does not work with `curl`. Removed and replaced with
plain text
`sed` arguments differ slightly from the linux ones. Changed to work in MAC OS X
Merge pull request #4 from fgierlinger/master

Added support for MAC OS X