CMS-1772 Convert schema_tree to use value objects

and

CMS-1771 Convert schema_list to use value objects

Converted schema_list and schema_tree to JAX-RS services.
Added tests for them, but they should be finished when style
of asserting of JSON will be decided
Merge pull request #317 from enonic/CMS-1772

CMS-1772 Convert schema_tree to use value objects