Description of problem:
Host parameters search does not return expected results when using the "!=" operator.

Version-Release number of selected component (if applicable):
nightly

How reproducible:
always

Steps to Reproduce:
1. Create a global parameter 'myparam' with value "1".
2. Override the parameter on one host with value "2".
3. Search for hosts matching "params.myparam != 0"

Actual results:
Only the overriden host is displayed.

Expected results:
All hosts are displayed.