BUG-1766: escape outbound strings

For non-numeric strings we need to make sure there are no stray
backslashes or double quotes are not left unescaped.

Change-Id: Ib2935ad7c4f483d4c592b3f8634d02c7383ba3aa
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-1766: escape outbound strings"