Command line option for slow test threshold

IMHO it should be OK to run long tests if we count with it.

Example:

    lynis audit system --slow-warning 300

Will warn when test takes longer than 300 seconds, instead of default 10.

1 files changed, 1 insertions, 0 deletions

diff --git a/lynis b/lynis
index 10f736c5..bfa1c308 100755
--- a/lynis
+++ b/lynis
@@ -453,6 +453,7 @@ ${YELLOW}Note: ${WHITE}Cancelling the program can leave temporary files behind${
     ${GRAY}--verbose${NORMAL}                         : Show more details on screen
     ${GRAY}--version (-V)${NORMAL}                    : Display version number and quit
     ${GRAY}--wait${NORMAL}                            : Wait between a set of tests
+    ${GRAY}--slow-warning ${BROWN}<seconds>${NORMAL}  : Threshold for slow test warning in seconds (default 10)
 
     ${WHITE}Enterprise options${NORMAL}
     ${GRAY}--plugindir ${BROWN}<path>${NORMAL}                : Define path of available plugins