Disk Utility not letting me partition my SSD or modify the current ones
You have several possibilities to repartition your CoreStoraged drive:


You may resize the Logical Volume Group non-destructively with diskutil
diskutil cs resizeStack LVUUID size. You get the LVUUID with diskutil cs list
You may revert the Logical Volume Group to a native volume
diskutil coreStorage revert LVUUID and check and resize the volume afterwards with diskutil resizeVolume DiskIdentifier limits and diskutil resizeVolume DiskIdentifier size. You get the DiskIdentifier with diskutil list.
Create new partitions with gpt


After repartitioning your SSD like that you won't be able to set-up Windows 7/8 with the default Boot Camp Assistant MBR-based method.

Most of the methods to efi-dual-boot/triple-boot/quadriple-boot require to completely erase of your SSD.

As already mentioned in the comments consider using Parallels/VMware Fusion and setting up virtual machines.