add eql? and hash methods to table object for using objects as hash keys

[nhemsley]

this makes airrecord objects usable as hash keys, before this change, each new add creates distinct key entries (unless it is the same actual ruby object).

This may not be wanted behaviour, but it should still detect records with dirty fields (serializable_fields.hash) and return not equal

Cheers for the library!

[nhemsley]

Actually I will add a couple of tests for this if you would like to merge:

test hash insertion doesnt cause duplicate keys & entries
test that changing a field causes eql? to fail
test that changing a field causes hashes to be nonequal

[sirupsen]

Can you fix the merge conflict? Then we can get this in :)

[nhemsley]

I will look at this soon.

[Meekohi]

Merge conflict and some of the tests are still using

walrus = Walrus.new("Name": "Wally") # Uses symbol -- no longer supported
walrus = Walrus.new("Name" => "Wally") # Use exact string

[nhemsley]

OK, merge conflict fixed. Please merge. Thanks.

[sirupsen]

This'll get released with 1.0.0, thanks!