Hal deserializer

Not ready to merge, do not review yet.
I needed to parse some responses in a cucumber scenario to have a Hal deserializer so I made this one. It covers the whole HAL spec, take a look at the files in spec/fixtures to see what it can understand. BTW thanks to @edandersen  of crichton-dotnet for those files.

I have deleted Representor because it was conflicting with the Crichton::Representor module in the Crichton gem. As it was you would not use this gem and the Crichton gem from the same code (and I need it)

I have created a new class from scratch called Golem, because:
- Golems are cool (Google for examples)
- Golems are your friends (or better are)
- It conveys the idea of creating something and animate it from inanimate materia (the document)

I am sorry I did not reuse the design for Representor we already had. I wanted to make it grow more organically (TDD, using the files as guide in fact). 

The usage of these classes is:
```Ruby
my_house = Crichton::HalDeserializer.new(some_real_state_document).deserialize
#now you can access properties 
is_big = true if my_house.room_count > 4
#access links
wget my_house.links.pay_rent.href
#access embedded resources
wget my_house.embedded_resources.kitchen.links.put_out_fire
 
#Alternatively and to access names that can not become methods there is a hash-like syntax:
puts my_house.links['self'].title
```

Please review and hopefully merge
@mdsol/hypermedia-team
@fosdev  @sheavalentine-mdsol  @brutski