refactors array-map tests so that they can be reused for other maps
removes order specific and seq tests out of the common map tests
Merge pull request #21 from mylesmegyesi/refactor-map-tests

Refactors array-map tests so that they can be reused for other maps
Allows dissoc to take 0, 1 or more keys
Merge pull request #22 from patrickgombert/dissoc-keys

Allows dissoc to take 0, 1 or more keys