Initialize the Table even when not creating it.

When not creating the table during initialization, if it exists, mark
the object as active and initialized.
removed overwrite option from save/put
removed overwrite documentation
Merge branch 'master' of https://github.com/TeamPraxis/dynamoose into TeamPraxis-master
fix masked error on describe in waitForActive
Merge branch 'TeamPraxis-master'
version bump - v0.3.1