Fix bug regarding free block type holders

When an application was deployed twice (or just any two or more applications
wit blocks that have the same UUID) then after shutting down the first the
others wouldn't free the BlockTypeHolders they used. Also only the
BlockTypeHolder for the last block with a given UUID added would be freed.
Make tryAdd in BlockTypeHolder synchronized

This made deploying multiple blocks on a single Modules sometimes
hang, probably due to a race condition.
Rename method

Method was called removeBlocks even though it only removed a single block
Fix bug in BlockTypeHolder.increase()

increase was unconditionally calling parent.increase() which led to
NullPointerException and amountLeft not being increased