Fix docblock variable name and whitespace.
Fix casing in method name.
More 2014.
Expanding and reformatting `respondsTo()` docblocks.

Refs 006c852.
Use native key prefixing for memcache adapter.
Check for key before incr/decr in cache memory adapter.
Adding tests for incr/decr in memory cache adapter.
Implementing increment/decrement for file cache adapter.
Refactoring file cache adapter; improve parser.
Cache file adapter incr/decr to not alter expiry.
Adding tests for incr/decr of file cache adapter.
Require increment/decrement methods for cache adapters.
Correcting documented cache incr/decr return and formatting.
Adding note about on-the-fly invalidation.