search - allow search on strings only

:Release Notes:
Ensure "search" accept only string as input, exception is for email format only

:Detailed Notes:
Ensure "search" accept only string as input

:Testing Performed:
Was tested on Starfish build 236.

:QA Notes:
correct request:
luna-send -n 1 -f palm://com.palm.smartKey/search '{ "query": "hallo", "context": "start", "quick": "false", "extended": false}'
wrong request:
luna-send -n 1 -f palm://com.palm.smartKey/search '{ "query": "hallo1", "context": "start", "quick": "false", "extended": false}'

:Issues Addressed:
[GF-10664] com.palm.smartKey:search - accepting numbers also

Open-webOS-DCO-1.0-Signed-off-by: Igor Kuksyuk <ikuksyuk@luxoft.com>

Change-Id: I971a26d3caec1cc51b6eb3d1fae95fca3b5d9f42
Reviewed-on: https://g2g.palm.com/2925
Reviewed-by: Build Verification
Reviewed-by: Igor Kuksyuk <ikuksyuk@luxoft.com>
Tested-by: Igor Kuksyuk <ikuksyuk@luxoft.com>
Reviewed-by: Roger Stringer <roger.stringer@lge.com>