redis: support of aeson 0.7.0 for issue #197
redis: fixed test suite to work with aeson 0.7 for #197
Merge remote-tracking branch 'origin/master'
version bump mongoDB for aeson
ignore cabal sandbox
existence of a nullable field should be optional

In MongoDB it already is except for embedded entities.

In MongoDB it saves space to have a non-existent field
rather than a null.
In addition, it avoids the need for a migration when adding a nullable
field.
Merge pull request #211 from yesodweb/embedded-nulls

existence of a nullable field should be optional
Use redis-server on Travis #210
Reduce number of Text to String and String to Text conversions.

Basically try to avoid String whereever possible.