Use *os.File for input/output files.

sshcrypt can now read from standard in and write to standard out.
Update docs and bump version number.
Move sshcrypt to its own directory.

--HG--
rename : LICENSE => sshcrypt/LICENSE
rename : README => sshcrypt/README
rename : TODO => sshcrypt/TODO
rename : kyle.pub => sshcrypt/kyle.pub
rename : sshcrypt.go => sshcrypt/sshcrypt.go
Move license, readme, TODO, and public key to root.

--HG--
rename : sshcrypt/LICENSE => LICENSE
rename : sshcrypt/README => README
rename : sshcrypt/TODO => TODO
rename : sshcrypt/kyle.pub => kyle.pub
sshcrypt README back to sshcrypt.

--HG--
rename : README => sshcrypt/README
Update TODO.
Split common functions into separate package.
Rename sshsign source.

--HG--
rename : sshsign/signer.go => sshsign/sshsign.go