A Ruby implementation of go-identicon by Damian Gryski
RubyIdenticon creates an identicon, similar to those created by Github.
A title and key are used by siphash to calculate a hash value that is then used
to create a visual identicon representation. The identicon is made by creating
a left hand side pixel representation of each bit in the hash value, this is then
mirrored onto the right hand side to create an image that we see as a shape.
The grid and square sizes can be varied to create identicons of differing size.