APT_U: Fixes for GetLockHandle to boot system titles.

- Also added comment to GetLockHandle function.
APT_U: Release service lock on initialization.
APT_U: Set a valid parameter buffer size in GlanceParameter.

- Also Clarified GlanceParameter/ReceiveParameter documentation.
APT_U: Added stub for function AppletUtility.
Merge pull request #188 from bunnei/apt-fixes

APT_U: Various improvements and bug fixes.