datastore: Introduce Key type.
datastore: Fixing regression test to support the Key type.
Fix lint error.
Fixing README samples with Key type.
Remove unnecessary handling for array type
Test case should be done when we acknowledge.
Merge pull request #102 from rakyll/fixregressions

Test case should be done when we acknowledge
Lowercase Key initializer.
Merge pull request #101 from rakyll/keytype

datastore: Introduce Key type
common: Avoid using require to read JSON file key.

`require` is not working well with relative paths.
common: add test for connection with keyFilename.