Fixed bug with blockplacevent. Fixes Bukkit- 5734

**Description:**
**Issue**
The changes to ItemStacks modified during the blockplaceevent that were the same as the itemstack being placed were ignored.
Before this change line 105 and 106 stopped any changes made when changing the amount of items in a stack during the blockplaceevent.
Using this code http://pastebin.com/WcseU4Lh you can tell in previous versions that it gets overwritten by those lines.  Removing those two lines allows the code to function normally as it did before this change: https://github.com/Bukkit/CraftBukkit/commit/da3f36250c40a0a664cfc07d188d2b0c4985086f

**Justification for this PR:**
Previous change broke a plugin that had been working for over two years.  Also breaks part of the api since the methods no longer work.

**PR Breakdown:**
Just removes two lines of code that set the itemstack to a certain value before the event is fired.

**Testing Results and Materials:**
Used any very later than https://github.com/Bukkit/CraftBukkit/commit/da3f36250c40a0a664cfc07d188d2b0c4985086f and plugin did not work as intended.  Made my modifications by removing those two lines and recompiled craftbukkit.  Plugin worked as intended.

**JIRA Ticket:**
https://bukkit.atlassian.net/browse/BUKKIT-5734