Added filtering capabilities to GetTaggedCacheKeys method, allows for retrieving cache keys by tag and filtering by regex.

Also added a simple file logger.
Fixed bug in LoadLogger and LoadSerializer methods when trying to load custom types. The condition to determine whether a custom type is of type ILogger or IBinarySerializer was incorrect, meaning custom types could not be loaded.
Fixed bug in ExtractControlBytes method. Added parentheses around messageLength calculation to avoid an issue with operator precedence. In certain cases, subtraction was causing messageLength to be invalid.

Removed unused usings. Added logging capabilities.
Added basic file logger.
Removed unused usings. Slight modification to Deserialize method - conceptually unchanged, just fewer lines.
Added Clear() method to clear cache.

Added Keys() method to allow clients to retrieve cache keys matching regex. Likely an expensive operation, but useful for certain cases.

Removed unused usings.
Added new commands processing to ProcessCommand method:

* keys-tag : allows clients to retrieve keys for a given tag. Can also filter keys by optional regex. Added GetKeysTagged() processing method to support functionality.

* keys : allows clients to retrieve all cache keys. Can also filter keys by optional regex. Added GetKeys() processing method to support functionality. Note: likely an expensive operation, use with caution.

* clear : allows clients to clear the cache (i.e. remove all entries). Added Clear() processing method to support functionality.

Adjusted commands:

* del-tag : now allows clients to remove keys for a given tag that also match an optional regex. Useful if you only wish to remove certain keys associated with tag. Added RemoveTagged processing method to support functionality.

* set-tag : modified logic for determining whether or not an expiration date was provided. Also cleaned up/modified expiration date extraction.

Other general code clean-up as well.
Fixed bug in LoadLogger method when trying to load custom logger type. Conditional logic to determine whether a custom type implements ILogger was incorrect.

Removed unused usings.
Added methods to support new functionality for del-tag, keys, keys-tag, and clear commands.

Removed unused usings.
Updated to VS2013.