Allow the redefinition of properties on subclasses

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>
Merge pull request #14 from PerfectMemory/inheritance-redefine

Allow the redefinition of properties on subclasses
deleted README link to README.md
moved Authors section from README.md to AUTHORS
bumped gem dependencies!
Merge branch 'cordawyn' into activemodelish
Add new types 'long', 'nonNegativeInteger', 'nonPositiveInteger,' 'negativeInteger', 'positiveInteger'

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>
Merge pull request #19 from PerfectMemory/new-xsd-types

New xsd types
Merge branch 'ruby-rdf-master' into activemodelish

Conflicts:
	Gemfile.lock
Merge pull request #5 from cordawyn/activemodelish

More updates from Activemodelish branch