Remove unused variable
Preventing from dirtying internals while creating a record with an existing id

[Fixes #768]
fix fixture adapter id generator

`generateIdForRecord` is called internally by ember on create
Cleaned unused variable
Merge pull request #782 from bobbus/clean-unused-var

Cleaned unused variable
Merge pull request #781 from tchak/fix-id-generator-fixture-adapter

fix fixture adapter id generator
Merge pull request #773 from tricknotes/remove-unused

Remove unused variable
Merge pull request #770 from Cyril-sf/bookkeeping

Preventing from dirtying internals while creating a record with an existing id