Hash calls now functions and one from each Family Option

Hash calls now all functions.

Add one from each family option, -o
    
Add an option to use only (-o) md5, sha1 and sha2-512

>$ ./multihash README.md -o
MD5    :  d41d8cd98f00b204e9800998ecf8427e
SHA1   :  da39a3ee5e6b4b0d3255bfef95601890afd80709
SHA512 :  cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2