std.hash review: Update 2

[Johannes Pfau]

Changelog:
* moved the package to std.digest:
    std.hash.hash --> std.digest.digest
    std.hash.md   --> std.digest.md
    std.hash.sha  --> std.digest.sha
    std.hash.crc  --> std.digest.crc

* make sure the docs are consistent regarding names (digest vs. hash)


Code: (location changed!)
https://github.com/jpf91/phobos/tree/newHash/std/digest
https://github.com/jpf91/phobos/compare/master...newHash

Docs: (location changed!)
http://dl.dropbox.com/u/24218791/d/phobos/std_digest_digest.html
http://dl.dropbox.com/u/24218791/d/phobos/std_digest_md.html
http://dl.dropbox.com/u/24218791/d/phobos/std_digest_sha.html
http://dl.dropbox.com/u/24218791/d/phobos/std_digest_crc.html