Fix for divide by zero in FixedRuler::GetPageFromPosition()

Fix for divide by zero in FixedRuler::GetPageFromPosition()

[problem]      A crash has been reported with a stack trace showing an integer
               divide by zero exception in FixedRuler::GetPageFromPosition().
[cause]        We have code there that divides by zero if a FixedRuler is setup
               with a domain that is smaller than its page spacing
               (a nonsensical state)
[solution]     Clamp the divisor to be >= 1 and log an error so the App devs can
               choose to fix the setup of the FixedRuler. Additionally, force
               the page spacing to a reasonable value at construction time to
               avoid a second set of possible divide by zero errors in floating
               point numbers.

Change-Id: Iae4fa025600c2ee54796fc458ca367d993c6ef66
Signed-off-by: Andrew Cox <andrew.cox@partner.samsung.com>