Add script for Martyr Ability for White Mage

Add script for the Martyr ability for White Mage. This is pretty similar to the script I wrote for Devotion. I already incorporated teschnei's suggestions for that script into this one. Similarly, this one also needs the targeting check in the script or it lets me cast it on myself; I'm not sure why that is, but the script check makes the behavior correct. Let me know if I need to make any adjustments.

Thanks!
-SLK

-Consumes 25% of Player's HP and Heals Double to the Target
-Merits add +5% HP recovered per merit (but HP taken stays at 25%)
-Player Cannot Cast on Self
-Stoneskin can absorb the damage if its up
-Ability fails if your HP is less than 4

References:
http://wiki.ffxiclopedia.org/wiki/Martyr
http://www.ffxivpro.com/forum/topic/36540/on-healing-hands-a-comprehensive-whm-guide/