Add active wait function

Add active wait function

Added function "wait_until_true". This function will make an active
wait until the predicate passed as an argument returns True.

If the timeout expires, the function will raise a generic exception
or a user defined one passed as an argument.

This function will be used in YARDSTICK-1127.

JIRA: YARDSTICK-1128

Change-Id: I9854e465ac6b586bf4be39ab4b266d5625b39e30
Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>
(cherry picked from 099108aab37d1fae1b27f4e2e20136c234df1a52)