Goal: Make LCache library more comprehensible by splitting tests into separate test classes that each correspond to classes within LCache.

I think the expected behavior of L1s and L2s will be easier to understand if the test suite is broken apart such that it is easy to see which tests apply to which classes. I think test reuse (via inheritance or traits) will also produce more consistency and fewer bugs across implementations of L1s and L2s.

Work to be done:

• Improve consistency within the existing test class: Improve consistency of tests used on L1s. #71
• Break apart test classes : (WIP) Refactor L1 tests out of LCacheTest.php and into separate test classes #72
• Improve documentation of tests (docblocks and inline comments). I don't have a branch started here yet.