Initialized variables and properties
Set SP_VALUE invalidation explicitly on failure

Previously the return value was set as null if the default argument
wasn’t passed simply because the default argument wasn’t set. This
explicitly sets things and makes sure the isHit value is also set
appropriately.
Fixed Docbloc, formatting
Type checks and documentation
Consolidated checkFileSystemPermissions

Tossed it to the Utilities class to get it out of the SQLite and
FileSystem handlers so as to reduce duplicate code. Formatting.
Formatting
Removed xcache driver

Sadly, my attempts to get the xcache people to support the CLI and
allow for testing has failed, and so this experimental driver is simply
being removed.
Cleaned up Composite driver
Further reduced duplicate code
Further consolidated PDO SQLite Drivers
Blarg, formatting
Initializing variables
FileSystem driver optimizations
Merge pull request #154 from tedivm/scrutinizer_refactor

Refactoring Internal Code and Documentation