Fixed attribute validation for attrs w deep diff
Minor version bump to 4.2.1
Bunch of minor bugfixes

* Updated locations for links and mixins
* Updated JSON rendering for mixins (depends)
* Updated specs (new locations)
Merge pull request #65 from arax/mixin_fix

Bunch of minor bugfixes
Fixed property handling for attributes
Merge pull request #66 from arax/prop_fix

Fixed property handling for attributes
Fixed properties for deep hashes
Minor version bump to 4.2.2
Fixed link rendering to text/plain
Fixed text/plain parsing of rel="..."
Fixed related_to? for mixins
Minor version bump to 4.2.3
Fixed rendering of standalone links and actions

* Fixed Occi::Collection (to_text, to_header)
* Updated specs
Minor version bump to 4.2.4
Merge pull request #67 from arax/coll_rndr

Fixed rendering of standalone links and actions
Fixed OsTpl and ResourceTpl mixins

* Removed deprecated 'related' and added 'depends' along with
  'applies'
* Fixed wrong mixin dependencies, kinds belong to 'applies'
  not 'depends'
Fixed ActionInstance handling in Occi::Collection

* Correct rendering of ActionInstance to JSON
* Automatic assignment with '<<'
* Enabled check (ATM just a stub)
Added ActionInstance support for Occi::Parser

* Added support for application/json, text/plain and text/occi
* Fixed AI instantiation in Occi::Collection
* Fixed attribute handling in Occi::Core::ActionInstance
* Moved annoying warn messages in Attributes to debug level
Moved annoying info messages to debug in Model
Fixed attribute handling in AI