Enable directive creation on dashboard

* fix attributes in quick search dropup
* fix nested-root-object/inheritance issue in Cacheable
Enable creation and edit of Directives and System/Process

* change model decision tree to handle multiple valid kinds
  for Contract, Regulation and Policy
* throws an error if the Directive kind is invalid
* fix ajaxPrefilter to skip param/deparam step (to maintain
  typed JSON content)
* add valid Directive meta_kinds in models and forms
* fix System/Process models
* handle/ignore invalid link IDs in some cases
* fix modal_title vs. title binding in some forms
* fix create/edit links for Directives/Systems
Make all objects' create and edit work

* fix model_content templates
* add 'update' to CanJS Model definitions
* add 'root_model' and use it for polymorphic links
* revert change to Cacheable's 'refresh', 'update', 'create' overrides
Remove 'owner' from System/Process form until reflected in database
Update Flask-Login dependency
Merge pull request #37 from reciprocity/feature/directive-creation

Enables/fixes creation/edit of all objects
Enable __null attribute queries

* e.g. /api/sections?parent_id__null
Merge pull request #38 from reciprocity/feature/null_attribute_queries

Enable __null attribute queries
Merge branch 'develop' into feature/rbac_clean