Inconsisten specification of contains

[jurajcik]

The contains is not defined consistently:

1. in https://github.com/persvr/rql/blob/master/specification/draft-zyp-rql-00.html#L457 as
   contains(<property>,<value | array-of-values>)
2. in https://github.com/persvr/rql/blob/master/specification/draft-zyp-rql-00.xml#L185
   contains(<property>,<value | query>)
3. in README.md
   contains(<property>,<value | expression>)
4. if I read the implementation correctly https://github.com/persvr/rql/blob/master/js-array.js#L59 it does support query/expression.

Could you pls correct draft-zyp-rql-00.html so that the definition of contains is consistent?
Also does query and expression have interchangeable meaning here? Would be clearer if you sticked to one of them in all documents or at least within the README.md.