Update gemspec to virtus 1.0.0
Fix deprecation warnings
Use types references as virtus attribute types has been removed
CoercedArray needs to be able to wrap other arrays so that results for + or concat can be of type CoercedArray.
Worked before due to different type_cache implementation in virtus
Remove setting a primitive type as it affects type_cache -> Leads to automatic coercion of NodeList in place of ANY array type
Forcing lazy evaluation of node as it doesn't work otherwise
Merge pull request #9 from airservice/upgrade_to_virtus_1

Upgrade to virtus 1