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
Updated specs to match the changes in AI
Minor version bump to 4.2.5
Updated Travis-CI config
Reverting a few stupid changes in Travis-CI conf
Merge pull request #68 from arax/mixin_fix

Bunch of fixes and minor updates