Fix issue where model without rules would not save

Signed-off-by: Bryan te Beek <bryantebeek@gmail.com>
Merge pull request #17 from bryantebeek/fix/1

Fix issue where model without rules would not save
Relocated $rules initialization so that array_intersect_key() can be used to auto hydrate
validate() was erroneously returning true for models with empty attributes against existing rule-set
Added $forceEntityHydrationFromInput property as per #15
Catches cases where an empty rule is listed

If a model a rule that is empty, e.g., 'name' => '' for whatever reason, the validation engine crashes.
This mod checks for any empty rules, and removes them from the array.
Merge pull request #19 from duellsy/patch-1

Catches cases where an empty rule is listed
Only add basic purge filters when purgeArray is called

Signed-off-by: Bryan te Beek <bryantebeek@gmail.com>
Merge pull request #20 from bryantebeek/patch-serializable

Only add basic purge filters when purgeArray is called
Added Ardent->purgeFiltersInitialized field to prevent multiple initialization of purgeFilters[]
use the Eloquent setAttribute method when autohydratation