Fixed boolean handling in Properties

*Moved code related to Properties from Attributes
*Fixed internal defaults for Properties
*Fixed rendering of Properties to Hash
*Updated specs
Added some restrictions on Attributes.new
Merge pull request #55 from arax/attr_parse_fix

Fixed boolean handling in Properties
Removing unnecessary assignment
Merge branch 'master' into specupdate
Preparation for parser specs
Fixed resource typing in Occi::Parser::Text

Occi::Parser::Text.resource is now using proper classes for
resource instances, i.e. Occi::Infrastructure::* instead of
a generic Occi::Core::Resource
Added spec for fixed resource typing
Simplified fix, using Occi::Core::Entity.new
Merge pull request #56 from arax/parser_fix_res

Fixed resource typing in Occi::Parser::Text
Only encapsulate strings in quotes in to_header()
Merge branch 'master' into specupdate
Do not exclude false boolean values from rendering
Attrs accept Occi::Core::Category as a valid type
Rendering specs for attributes
Specs extended to cover properties assignment
Unfinished attempt at fixing .parse