[impala] Some URL refer to neeswax instead of impala

Downloading a result
Saving an Impala query should not redirect to Beeswax
[impala] Specific query configuration can be overriden

Also propose an Impala property instead of Beeswax
[impala] Downloading a result not cached anymore should fail more gracefully
HUE-1946 [beeswax] Can't select and execute more than one query

The previous statement of a multi query can be closed so the previous
result can be expired.