desc: reject non-deterministic secondary indexes (#579)
tests:

  - cd: r.db('test').table_create('579')
    def: tbl = r.table('579')

  - cd: tbl.insert({'name':'Jim Brown'})

  - js: tbl.index_create("579", function(rec){return r.js("1")})
    py: tbl.index_create("579", lambda rec:r.js("1"))
    rb: tbl.index_create("579") {|rec| r.js("1")}
    ot: err("RqlRuntimeError", "Could not prove function deterministic.  Index functions must be deterministic.", [])

  - js: tbl.index_create("579", function(rec){return tbl.get(0)})
    py: tbl.index_create("579", lambda rec:tbl.get(0))
    rb: tbl.index_create("579") {|rec| tbl.get(0)}
    ot: err("RqlRuntimeError", "Could not prove function deterministic.  Index functions must be deterministic.", [])

  - cd: r.db('test').table_drop('579')
